Really cool and unique idea. It reminds me a lot of the Tony Hawk Pro Skater games I used to play and much like those games, it was really fun trying to string together a long combo.
One small issue I had was with the balance meter for grinding and manuals. Since they don't seem to reset during a combo, even if you haven't done a grind or manual in a while, I had times where I would start one and instantly bail. I guess partly that's on me for not keeping my balance better, but it also felt like sometimes I had no chance to correct myself.
Other than that, it was really fun. Rad game!