Just to hammer out all 3 of these at once, I'll spam the last one that I beat just after midnight, Sonic & Knuckles.  What I said about Sonic 3 still applies, but on top of that this game just seems weird.  I even just had a conversation with a friend about it, who said they had little time to develop the game apparently.  I went through it as Sonic, and in the first level I'm jumping off of mushrooms, pushing down vine ramps, and roosters are blowing me (hot), and all kinds of other weird crap.  It doesn't maintain that level of weirdness throughout the whole game, but it does other things like hanging from rungs, or doing one or two pseudo-3D things.  This stuff struck me as so out of place, especially coming right after playing Sonic 3, that I almost wonder if THIS is where the series went off the rails as opposed to Sonic Adventure.   I mean hell, in one level there are GHOSTS trying to kill me.  Because really, what else are you playing Sonic for?  Aside from that, while the levels were more interesting, the music I thought got even worse, and there were several points where I kept dying to figure out how to make a jump or where to go, which left me even more frustrated than I was with Sonic 3.    Now that I've played this and 3, I feel like I can definitively write off the series now.  I pretty much did after Adventure, but this makes me feel better about it since now I know for sure what I was missing in that gap in my personal Sonic timeline.
 
2 out of 5 stars.