Hmm, i think i made it quite easy :p,
As, it gets faster the longer you survive and obstacles don't start spawning until a good 5+ seconds in so you get to feel the controls pretty well.
The challenge is the small learning curve on knowing which projectile to shoot, and which obstacles are worth shooting with rockets etc.
Personally, I think the difficulty curve is quite good right now, without making it boring :P
Thanks for feedback though :D