I had a funny love->hate relationship with this game back in 1999, when its many flaws overshadowed the things I initially enjoyed about it. Now that I've been replaying it again, I actually like it a lot. But let's look a bit closer.
Much of the feel of classic 2D Genesis Sonic
games has carried over to this one. The level designs tend to contain many of the elements of the older games, although in 3D. Sadly, the levels are very linear and rather lacking in alternate routes, something the 2D games had a great many of - something that dragged it down considerably once my views had started to sour. Alternate routes tend to be short and very quickly get reassimilated into the main path.
At one point I disliked the adventure fields, because I was starting to prefer the straightforward "level-by-level" progression of the Genesis games. Initially, I liked running around the town at high speed, finding the occasional powerup (some of which are hidden), talking to the townspeople, and seeing how the adventure fields connect to the game's levels. Many of the townspeople have their own story mini-arcs (striking train workers, a kid waiting for her dad to come home), and it was neat revisiting the same person to see what they had to say next.
The one element that I feel just works and makes much of the game come together, is the one thing that is most important in any action game: play mechanics. It's fun being able to run at amazing speeds from a standing start, and the physics involved with slopes and jumps can result in absurd stunts like rolling up a slope and jumping right before the edge to launch 5 stories into the air and land on top of a temple. I feel the game would have been better if it had taken more advantage of what can be done with these mechanics.
Sadly, Sonic only has 10 levels to go to. Other characters are okay storywise (and I happen to like Big the Cat), while their gameplay styles are not as much fun. There are also various mild problems (invisible walls in town, glitches with loops and launchers misfiring, bizarre and awkward lip syncing animations) that hold the game back. Some of these add a So Bad Its Good
feel to the game in hindsight, and my brother and I have been having fun revisiting it while cracking jokes at its expense.
While it may have fallen under its ambitions, I still feel this game is good overall.