You're right about the title music, at least...I have a beta of it with different title music which sounds much nicer. Sounds almost like the notes got mangled in the MOD->Jag conversion process; it's very odd.
Agreed on the collision - it's odd. You can hold down to reverse when stopped, which helps a bit. I especially hate the 'castle' levels with the totally unforgiving walls, but as you get better at it you notice it less. Almost makes me think the testing was done by the design team, or at least people good enough not to notice it. The repeating levels isn't quite true - you get repeating level elements, though the levels do change: the elements get strung together in different orders, is all. I've also found the later (latest...) levels get impossible - right now I'm stuck on Firebug's level. Just cannot do it; very infuriating.
I'd have to say it's one of my fave Jaggy cart games though, excellent fun
Stone