When I first played SA, it was only for a few minutes, so I can't say I really had an opinion.
I'll move forward to when I saw (and later played) SADX:
I didn't see much glitchy stuff, but I remember the load times seeming too slow and frequent.
(Mainly because the Egg Hornet battle was part of what I saw.)
When I got the game, it seemed okay, but a bit frustrating.
Of course, Big's A missions had something to do with it.
So did certain new missions, such as the Tails Icecap one (with flags).
Of course, I got past that and loved the glitches.
SA2 seemed to be kind of better in some ways (way longer),
but like Crazy Penguin said, many problems were just ones that
SEGA wrecked more instead of fixing. (See his post and also magnum12's.)
The camera, lack of Adventure Fields, and worse glitches* discouraged
me from looking for cool glitches and shortcuts.
(*SA's glitches don't get in the way as much. There are a lot, but most of them
are just wall and corner problems, at least for casual players.)
Oh, and there's the problem of the rankings and missions.
(It mostly just rewards high scores, and not fast times.
It wasn't too fun to play 3 nearly-identical missions for scores.)
SH was just sloppy. I think I might start to like it almost as much as SA2 soon,
but it didn't seem like a full Sonic game. The story wasn't just simple...
it was bad. It copied bits of other games (mostly SA) and resulted in
a mess of old stuff I had seen before and other dumb problems.
("It could be YOU-KNOW-WHO!"... yeah, really well-written!)
The gameplay is too slow and fighting-based, and the control is worse than ever.
(what it has for a spin dash randomly fails, which is really bad with Team Rose)
One more thing: The Adventure Fields added to the realism, and I kind of liked them
(and not just for the glitches). Unfortunately, SEGA did a bad job of connecting areas.
(If I get the PC version of SADX, and if it's possible, I want to edit the fields and
add new objects to the backgrounds. It would be really cool to see the game
with one of the major flaws in the graphics and realism gone.)