Alright, so I spent about 40 or so minutes with this, and I can say that I don't think I really like it for one simple reason: the phasing mechanic is not balanced properly.
I like the idea of switching your color for boost pads. I also like the idea that when they're on the ceiling you need to match your color and flip upside-down. I do NOT like the idea that you can't switch at will if you don't have a power-up to do so.
Granted, it's the only power-up in the game, and you can store several at a time. But if you boost along a straight away and drain your meter (they use the same one, boosting just takes more energy, like four instead of one), you can really screw yourself if you're heading straight toward a wall and need to switch for a jump pad.
Should you need to learn the tracks? Yeah, this will help prevent you from draining your meter completely when critical spots are coming up. But there doesn't seem to be a free-play mode in single player to do so. And if you drop from first to fifth in FAST, there's next to no chance you're coming back to win against the computer because there's next to no variance in how they race -- they're like perfect, pre-recorded ghost laps and boost at what seem to be the perfect points. I found that if I boost into first place right away and race cleanly, the computer can't touch me either and I'll spend the entire match two to five seconds ahead. The game is missing some sort of variable to balance that out.
It's a shame too, because the makings of a truly great racer are here, but these two details are killing it for me so far.