I rather enjoyed Sonic Generations even though in my opinion it was way to short. I don't like beating a game in one day. Granted, I could go and get Rank S on every stage, but that doesn't unlock new stages or cinematic.
Anyways, I don't really have a problem with Sonic games. I'm not sure why most people seem to hate the newer Sonic games. Side-scrolling games aren't practical for a console game for the most part. Mario doesn't do side-scrolling anymore so why should Sonic?
I think the only problem with the decline in Sonic's success is originality. Same hero defeats the same villain in the same way in every sequel. Is anyone interested in Sonic going up against a villain that's not Eggman? I sure know I am. I thought the dark villain for Sonic looked epic, then I got the game and found out it was just Eggman controlling it.
The graphics were superb and I didn't notice any glitches in Generations. The whole revamping old game stages to both Sonic gameplay types was pretty good in my opinion and I loved the music, as always.
I kind of wish they'd bring back Chao gardens to the newer games. As unpopular as the chao gardens might be, I found them to be extremely enjoyable. xD Haven't seen that feature since the Adventure/Advance games though.
I can't wait for the next Sonic game, actually. I'd like to play as Shadow, Tails, Silver etc. though. I think that would be interesting if there was an individual storyline for each character so you can see the plot from that specific character's point of view.