I can honestly say I would have rather this be only car racing. This whole changing vehicles mid race thing is a ridiculous gimmick that excuses changing the controls arbitrarily on the racer.
And the plane and boat controls are so horrendous, someone used to playing say, Mario Kart games will be absolutely lost. It's not a BAD game, mind you. But Nintendo already did racing better. I do like the trigger for acceleration, that's about the only improvement here. I wish there were exclusive car, exclusive air and exclusive boat gp's and tracks so I wouldn't get destroyed in the air and boat portions of any given race, though.
And the D list videogame "celebs" in this game are pretty laughable, too. This is definitely must be a Sega fanboy to enjoy to its' fullest. Honestly, I wish there were a sideways thumb option on steam.