Great characters.
Blaze being great is pretty self evident, she has good sprite work, her slow fall from Rush, a mild double jump thing to sort of cover her tricks (and also it's good), and even a well integrated boost mode.
But what's less obvious, at least for someone like me who only downloaded for Blaze, one of the coolest Sonic characters, is that Marine is pretty great too. She's basically Racoon Mario, with all the fun that implies, plus her spritework is up to the same high level as Blaze.
I still haven't gotten the Sol emeralds, but I don't really like super forms that much anyway. (It would be nice if there was an option to disable the special music for the Chaos Emerald secret, though.)