From what we can tell, the title is sticking to what made the first so successful. Blaze the Cat will be playable in addition to Sonic, but the game sticks to the trademark mechanic of blinding speed to entertain the player. There does appear to be some actual "adventure" portions of the game, but they merely consist of a (high-speed) boat ride across a three-dimensional ocean, a la Wind Waker. Also, the Sonic team has finally decided to give Sonic the gift of everlasting respiration, removing the classic "air bubble" gameplay found in underwater levels.
With some snazzy 2-D to 3-D transitional effects and intriguing level design, we've no doubt that SRA will match, if not exceed, the original. Keep your eyes peeled for the azure blur this fall.