SA2 was in some ways better than the forst and in some ways worse. The Knuckles and, erm. bat lady levels were horrible. The Sonic and Shadow stages were awesome.
I still think the first was the best though. And easily the best 3d Sonic game. There were flaws (like Big the Cat) but there always were in Sonic games. Sega were always erratic, they aren't Nintendo, but when they were good all the niggles were worth it.
Yeah, it was more of a 'game' than the first one, but I still preferred the original because of its freshness. I was totally amazed the first time I got the console and popped in this game. That first level is such a great advert for the console, its so fresh, fast and exciting. I never completed the game or the sequel, I must get round to doing it one day.