For interest's sake, I constructed a tier list to compare with whatever list comes out of the MBR in the ensuing months. To sidestep any potential conflict: this is -for fun-, tiers are -not- the most important thing in determining character choice/factoring in who will win a match, I do know who Gimpyfish is, and piss off for mentioning I have too much free time on my hands.
I expect Brawl to be less oriented towards effective range than Melee, and more dependant on the area a character can control with respectable power.
FRACTURED TIER LIST IMPENDING
Top
ROB-ROB has Peach's downsmash, powerful and spammable projectiles, good speed, a spike, crazy di (more than even Jigglypuff's), and he's of respectable weight. Oh and there's his godly recovery. ROB can ascend while using his upb for a whopping 5 seconds, during which time he is able to attack. That 5 seconds doesn't have to be used all at once though, so you could jump, ascend, jump again, ascend again, etc...basically he has a vicious wall of pain style strategy. Sounds like ROB will be able to fight well at close and far ranges, which no other character has ever been able to do.
King DeDeDe-DDD has very good recovery, extremely powerful moves (he can ko Mario at 17% on FD with a fully charged fsmash...while it neglects di that is still awesome), a spammable projectile with decent damage and knockback, he's floaty, he's heavy, his attacks are fairly quick, he has a chain throw, and from the looks of things DeDeDe has a disjointed hitbox. He's a large and slow target sure, but DDD sounds like a total beast.
Marth-Tippers are back! Marth is -the- definitive edgeguarder and his moves pack a punch, which is even more important now that Brawl is a floaty game. Marth also gained some in the recovery department with a b move that has very little startup and can gain him horizontal height. I don't know if his chainthrows are back...but Marth kept almost everything that made him great in Melee, and benefitted heavily from the need for ko power.
Lucario-Lucario sounds formidable as well. Lucario has good recovery...if he hits the side of a stage while using his upb, he's able to climb his way up to safety. No joke, look into it. He's also very fast, fairly heavy, floaty, and with strong attacks that come out quickly. Also of note is that he has a unique property-the more damage Lucario takes, the more damage and knockback his attacks deal (up to 2x damage/knockback at 200%). So basically you have a character that's hard to ko with dynamite moves that becomes -stronger- as you beat on him. Fearsome.
Upper
Olimar-People have INSULTED ME for saying Olimar will be obscenely good but Olimar will be obscenely good. He can churn out Pikmin very, very quickly with pikmin pluck and spam them easily with pikmin throw. A defensive Olimar sounds hard to defeat...if he produces purple pikmin and sits there, it's going to be difficult to get through to him...he's also a small target, which definitely works in his favor.
Zero Suit Samus-Do I need to say why ZSS will be awesome? Basically she's fast with Sheik's tilts, Falco's laser, good recovery, can actually combo, etc. etc. etc.
Falco-Falco's laser is stronger, and his downb can be thrown for better range...sounds like he's more or less what he was in Melee, with some significant improvements. Though he doesn't have ko power, Falco can still snipe opponents from far away and hold his ground, punishing anyone who advances. For such a good character, he didn't really fit the meta then (speedy, needling characters on top) and I don't think he will now (from the looks of things powerful characters with good attack range).
Wolf-He's a slower Fox with more attack power, better range, an amazing reflector (check out its size), and superior recovery. Wolf just has a lot going for him.
Meta Knight-MK has lost a lot in my book for lack of powerful moves, but he still has combo potential, a disjointed hitbox, speed, strong aerials, and multiple jumps/good recovery. We may have overestimated his capabilities, but Meta Knight will still be powerful.
Peach-Her godly dsmash has been toned down but turnips and float cancelling are back, and her bair has been improved from Melee...Peach will be good for the same reasons she was in Melee, even without her brutal dsmash.
Pit-I still say Pit will be a very good fighter. He has good combo potential (a rarity), very good recovery, strong aerials, and edgeguarding skills...if Pit can knock someone off the platform then it's pretty much a free kill.
Middle
Pikachu-Pikachu has been severely buffed in Brawl, with added attack power and reduced lag on his moves. Pikachu is more like the SSB version...with infinite range on thunder, thunder spiking is back, his aerials have been improved, his smash attacks are still powerful, etc. etc. etc. Pikachu will still have range problems I think, but they won't be as amplified as they were in Melee.
Kirby-Kirby's been improved from Melee, now that his aerials have fewer startup frames and cover more or less the same range as they did in SSB. Kirby's fair also extends his recovery, compensating for his recovery problems in Melee. His throws can be executed faster as well, making a kirbycide easier to pull off.
Captain Falcon-From what I've heard, CF's moves are still powerful...and he's still fast! This is a very good combination and I do not feel like explaining why.
Bowser-Bowser has been buffed since Melee. His moves are stronger with less lag, he's reportedly faster, his throws have been upgraded, his recovery has improved, on and on and on. I don't think it's enough to make Bowser -that- good, but from the looks of things he'll at least be playable.
Fox-Fox has taken a hit without waveshining and foxtrotting returning, as well as with the floatiness of the game...however his uair can apparently score multiple hits and has more range, so I'd say he's still going to be a solid fighter.
Ganondorf-I've seen very little of Ganondorf in action, but it looks like even though he's slow his attacks come out quickly, and his recovery is marginally better. If that's the case then Ganondorf will be a decidedly average fighter.
Sheik-I've heard rumors that her chainthrows are out, so Sheik lost a lot in the punishment department...tilt combos also don't look like they're feasible anymore, and Sheik's inability to kill at low percents will cost her. Then again she still has needles and such.
Mario-Mario -defines- character balance...as far as I see it he's pretty much unchanged from Melee since FLUDD is useless and the Mario Tornado is an aerial.
Luigi-Luigi is better than he was in Melee. His slow falling speed, poor traction, weak ground game, etc. have all been improved...his recovery has also been bolstered since Luigi can jump higher and the super jump punch goes further vertically. He still isn't as good as Mario, but he's more usable than in Melee.
Low
Jigglypuff-I expect that rest combos will become even more necessary for a Jigglypuff player, now that -everything- dies at high percents. Jiggly will, I think, be subpar as a fighter.
Toon Link-WW Link has a few things going for him, but not too much. His dair ("the pogostick") is very easy to get in, and you can use it to damage your opponent almost indefinitely...it's a solid punishing move which will lend itself to a decent wakeup game. He also has solid aerials. His upb is very damaging, and with a strange trajectory hard to target...I see the potential for some very interesting mindgames. TL is also fast...and then the praise ends because he's light, his recovery is bad, and he doesn't have a kill move.
Ike-He has fairly powerful attacks and is heavy with a disjointed hitbox, but his poor recovery and attack speed will hurt his usage.
Sonic-The only things Sonic accels in are speed and recovery...his attacks are weak, comboability is difficult, he doesn't have much range, and on and on and on.
Lucas-Lucas is basically Ness reworked. His PK fire move is surprisingly damaging and he's deceptively strong...but he also has bad recovery, so-so speed, and a light weight.
Ice Climbers-Desynching is back, which means they can chain throw...however, the IC's are abysmally slow without wavedashing and they play a generally poor aerial game. In spite of their strong smash attacks I don't see them playing too well, mainly because their attacks have a lot of startup lag.
Donkey Kong-Not much changed for Donkey Kong. He's still moderately fast and heavy, which is a plus...but then he has bad recovery, he isn't really powerful (as seen in Famitsu's 'top 3'), he has poor range, lackluster aerials, and generally isn't a good character.
Diddy Kong-Diddy Kong is fast and weak with bad range and passable recovery. I do not feel like explaining why this is a bad combination.
Samus-Samus' missiles and chargeshot have been absolutely butchered from Melee to Brawl, so her biggest strength is gone.
Bottom
Link-Link can no longer spike with his upb, so he's a slow character with little power and a shallow playstyle.
Game and Watch-He's bad for the same reason everyone this low is bad...he's slow with crap range and weak attacks. I have seen nothing that would lead me to believe he has been improved from Melee.
Zelda-She's been slightly improved from Melee, but not enough for her to be any good. She's still very slow, light, a large target, and her attacks are laggy.
Yoshi-Blah.
Ness-Ness' attacks are weak, they're laggy, he has bad recovery, he's slow, and he's light. I can think of no redeeming attributes of Ness.
Pokemon Trainer-The pokemon aren't very good...of the bunch only Ivysaur looks like he can combo and kill reliably (Squirtle has problems with range and a general lack of power while Charizard's attacks come out very slowly), and you can't play a single pokemon as PT.
Snake-Snake looks fairly weak and slow, so I'm not expecting much from him. He can potentially edgeguard with his mines/projectiles...but the moves that can actually get the opponent to the point where they're knocked off stage are lacking.
Wario-I overestimated Wario's prowess...even at full power the Wario waft has piddling knocback, his recovery isn't good, and his attacks are slow to come out. For a powerful character, he...isn't, he's only marginally more powerful than most fighters.