One excellent game
Firstly, that's a brilliant game. Just making sure you know what i mean!
Secondly, there's just a couple of things that you might possibly be able to work on for subsequent versions if you do them:
1. Spikes hurt you whether you stand on the spikey end or not - in Sonic you could stand on the sides of them etc.
2. The angle necessary to jump onto a ledge is really quite tricky at times - i'm not sure if you meant it like that, but it gets a bit frustrating!
3. Sometimes there are clipping errors where you go from one sort of terrain to a curve, which stops your 'run' - while not a major problem it would be great if it could be ironed out.
Apart from those few little things, it's excellent. Keep it up! :)