I haven't actually played any of the new Sonic games (apart from demos) because I read such bad things about them all.
You sound like me, I love the feel of the old ones, and this one probably would end up being a disappointment for me.
I thoroughly enjoyed Sonic Adventure 1 and 2 on the Dreamcast, especially the challenges/timetrials/secrets. Spent a fortune on batteries for my VMU training up my chao

Now where's Sonic 4 for Steam!?