Those choices are pretty unconventional, Kysarin. But you support them with good logic. It's nice to get a change in perspective every once in a while.
I think that overall, Sonic Heroes has gorgeous, well-defined visual themes for each zone, contributing to a satisfying game structure similar to the Sonic titles of the early 90's. Furthermore, the background music usually compliments the atmosphere of each individual act very well (for instance, the easy-going Casino Park tune is just as appropriate as Bingo Highway's frantic theme) Aesthetically speaking, Heroes was a success at least to the extent of Sonic Adventure and its sequel.
The thing that ruins Heroes for me is the squandered level design. We all know that the levels are too linear and too lengthy and too boring. The very worst thing, though, is that the game's truly innovative and interesting control scheme is largely negated by a serious lack of exploration. I mean, the player controls a highly maneuverable team that can run, fly and break its way almost anywhere. How the developers of Heroes failed to recognize this set up as highly conductive to open-ended, sprawling exploration-based levels is beyond me. Instead, the final product featured some of the most tedious marathon-lengthed obstacle courses ever. They're pretty obstacle courses, mind you, but obstacle courses nonetheless.
As for Sonic CD... I believe most perceptions of that particular game depend on what you value about the Sonic series: Graceful flow through levels, opportunities for through exploration, or a mix of the two. I happen to like my games with plenty of exploration, so I don't mind hopping freely through the cookie-cutter level design of CD. This is in stark contrast to Sonic 3 and Knuckles, which usually forces the player to go through a limited number of self-contained paths through any given level. It could be interesting to debate the respective merits of Sonic CD and Sonic 3 and Knuckles's specific approaches to level design.
Hey Kysarin, have you listened to the Japanese soundtrack of Sonic CD? It could be more up your alley.