The music hits, instant nostalgia. But as a whole, this is probably the weakest level for Classic Sonic so far, as it's got the most problems out of any stage. Too much stuff of the foreground, the visuals are pretty dark and kinda bland. There's also a lot of awkward platforming moments where the gaps are just wide enough that you had to stop, set yourself, and jump just as the right spot to access certain sections of the level. It's nothing major, just a lot of minor troubles that keep it from replicating what made the original Green Hill Zone so good. Fortunately, a lot of these problems don't crop out in later levels.
Rating: C+
Act 2 - 3D Modern Sonic
I've played through this many times in the demo and I remain pretty impressed with it. There's a good sense of speed, some alternate routes to use to access new and different areas. There's a bit of memorization required to get the perfect run, but that's been true of Sonic since the Genesis days. My only complaint is that stupid purple stuff that I always forget about and always trip over it, killing my momentum.
Rating: B-
Winner: 3D Modern Sonic
-- TheRock ~ Death By Misadventure, Not Suicide "Would've liked to see that." - Ayuyu on my boner
I try my hardest not to compare the 2D Sonic levels to the originals, but it's just so damn hard. This version of Chemical Plant Zone seems a bit slower, with few moments where you're just burning through for long periods of time (like the tuuuuuuuuuuuuuuubes). This is definitely a bit more platforming heavy than the Genesis version. Still, an improvement from Green Hill Zone. Most of the issues from that are gone, and Classic Sonic settles in nicely to his groove that doesn't change much from level to level.
Rating: B
Act 2 - 3D Modern Sonic
Wow. Just... wow. This may sound like hyperbole, but this might be the best damn 3D level ever made. Good bits of platforming, excellent use of multiple paths, great moments where you're just zooming along, a water pipe! And that remix. I remember thinking "You can't remix Chemical Plant Zone, that's one of the best Sonic songs ever!" And yet, they created something that's both unique from the original, but still both borrows from it and creates something awesome. Its the first level outside of GHZ that I've played the main act several times over. I wish I could describe better that makes it awesome. There's a great side-step section avoiding bombs. There's some great platforming using the shifting blocks (I think I like 3D Modern Sonic's jump a bit more than 2D Classic Sonic's. Yeah, it's a bit floatier and I miss the double jump a bit, but I like a jump that goes further and gives you more time to react on the way down.
Rating: A+
Winner: 3D Modern Sonic
-- TheRock ~ Death By Misadventure, Not Suicide "Would've liked to see that." - Ayuyu on my boner