I only played the first two tilt levels and just skipped the rest - I'm really glad they're not a barrier to progression as find them a bit annoying and an unwelcome change of pace when I want to get on and see the next story mission.
Treating them as a skippable bonus is quite the smart game design decision, really.
In fact, the game design is so smart that almost every time I've been stuck for a couple of minutes a tip has popped up or it's dawned on me that I've been going about something the wrong way.
As frustrating as the latter can be, I have to say the smile I have when I suss out a game mechanic or puzzle far outweighs the bits that have stumped me. Sure there are a couple of levels I'd not play again more than once, but more often than not this game is doing something right.