When people complain or praise, it's always for the wrong reasons.
(The ironic thing is that Gamespot hates the Daytime stages yet praised Sonic Advance 2 and Sonic Rush)
I don't hate the daytime stages because they are too much for me, they are UNDER-whelming, you see, what is Sonic, a racing game or a platformer, I'll give you 5 seconds.
Done? Okay, well, if you picked platformer, good, and that's where this game fails, not because the daytime stages have horrid platforming, it's because they have almost NONE.
The 3 elements you need to make a good Sonic game is platforming, speed and exploration, you can't have a good Sonic game with a single one gone, you need all of them healthily blended together.
The daytime stages are ONLY speed, press X and relinquish control of Sonic unless you need to perform this game's pathetic excuse for player interactivity; quicktime events and sidesteps, and you need the sidesteps because Sonic controls like a tank and you can't naturally move him to the side, but this just gives the player THAT much less to do, and there's a lot of side step sections.
This game even punishes the player WITH platforming, say you hit a ramp and you didn't boost into the rainbow ring to send you flying, you have to go through a platforming section.
Some call that exploration, but no, the closest thing to exploration in the daytime stages is choosing where to go when you see a split in a linear road.
In the classics, Sonic Adventure and Generations, you could go anywhere in the level because of how great the exploration was, and when you dare to venture off, the player is rewarded, say they get rings, or a shortcut, or invincibility, or whatever to make it more fun.
The daytime stages aren't fun, the feeling of everything whooshing by just makes this game dumbed down.
They aren't long either, while they might take 5 minutes to beat, it's because they are more like a stretched rubber band because it really is one short thing (press X to win) but done for too long.
When I think of fun in a video game, I think of the rewards for or great feeling of surviving the challenge, and this game really isn't hard.
Now lets talk about the Werehog stages.
They don't really make the game worse, but being inappropriate for a Sonic game, it kind of does.
The sad part is, the Werehog has most of the platforming, and most of this platforming is decent.
People hate it because, well, they were expecting something Sonicy, but if you realize that the Werehog isn't meant to be like that, it's a bit more enjoyable.
While long, the Werehog levels are a bit less of a stretched rubber band because of the platforming, though they are still linear.
The combat is actually pretty cool, but out of place in a Sonic game, but the biggest problem with the Werehog is that he's too slow, the Werehog was implemented because the daytime stages were too fast and Sonic needed to slow down, simple solution, platforming, but they really over did the low speed with the Werehog.
I wish that Sonic Team could've found a middle ground so the Werehog levels are fast enough and the daytime stages are paced enough, but the daytime stages are one extreme and the Werehog is another extreme the opposite road.
Aside from that, the Werehog stages are "okay", but it's the daytime stages that bring this game down.
If you are one of the people who like the daytime stages, you are the reason for the spree of bad Sonic games in 2002 - 2009