According to GameFAQs , major patches addressed:
Chaining stunts (up/down flips or left/right rolls) with the right thumbstick is the primary way to stack turbo boosts. File: Sonic.and.All.Stars.Racing.Transformed.v1...
Early updates for the Wii U version were notorious for a bug that rendered "Boost Race" levels unwinnable by removing checkpoints. According to GameFAQs , major patches addressed: Chaining
Explain that vehicles dynamically shift between car, boat, and plane modes upon passing through blue gates. Corrected cases where the HUD incorrectly displayed "Lap
Corrected cases where the HUD incorrectly displayed "Lap 2" and fixed issues with favorite characters in licenses. Gameplay Mechanics to Feature
Note that versions differ by exclusive characters: Xbox 360 features Avatars, Wii U/3DS use Miis, and the Steam version includes characters from Team Fortress 2 , Total War , and Company of Heroes 2 . Modern Compatibility Sonic & All-Stars Racing Transformed | Sonic Wiki Zone
Better handling of "physics tunneling" for very fast players to prevent driving through walls or objects.