Doomsday was suitable for what it was, but agreed that its not the best of its kind. Besides that, all the music in Sonic Unleashed thus far is mouth-watering (except maybe Empire City, but that fits and I'm not going to have to deal with it on the Wii version anyways =P).
Still waiting for Gamespot's review, they are another strong critic of Sonic, but they don't seem to have been as vastly interested in Sonic as IGN this year. On the other hand, they were really expecting Sonic Chronicles to be the best Sonic game of recent days. IGN's review was very predictable, though unpredictably rated... but I'm not quite sure how Gamespot feels about everything as far as opinions because of the lack of previews.
I believe most reviewers are fans of rollercoaster gameplay, with the few complaints against it being the overused "plays-itself". To be honest, I feel that there is where Sonic has finally found his niche in 3d gaming, and while not expanding much on the 2d realm the way Mario's transition did, its become a little bit more unique and fun. I've said before I prefer Sonic in his own genre... but there are times when I'd like to play some normal platforming in a Sonic game. Fortunately for me, Werehog seems to satisfy me as far as official games go, and I can always make my own levels for SRB2.