So I went back to play a bit of Episode 1 yesterday, and the difference isn't exactly like night and day, but there certainly is a marked difference between the two.
The artstyle in Episode 2 is so much better, and Sonic handles better in Episode 2 as well (except for rolling and going down slopes (ie: for some reason his speed is constant as opposed to going faster and faster).
I think the level design in some parts is better than Episode 2. You aren't colliding into enemies or bubbles when you go high and uncurl (and thus hit the enemy and lose your rings) like in Episode 1.
Music's better in general as well, but it kind of feels like the loops in Episode 2 are a little short? It might just be me. But with that said, it's not like that music in Episode 2 is stellar or anything. It still has problems.
But the overall feeling I get from both of the games is that they're just 'there'. They don't really do anything substantial or special that adds to the series too much. You can argue that Team Attacks in Episode 2 (as opposed to the attacks in Sonic Heroes) might be something 'substantial', and when they work pretty well, yeah, they're kinda fun to use. If they improve on team attacks for a theoretical episode 3, then it might be fine. But as of right now, I'm not really getting much out of either game.
I don't know if you can do it as regular Sonic (never tried jumping at them), but you can use the Tornado's spin attack to knock the cannonballs back at Metal Sonic.
You can't. I tried. :lol You have to use the Tornado for that, I guess.