Great for a first, nice atmosphere!
BUT, what some have already said, it's really frustrating to get through. The jump may be the main problem, it kind of feels 'stiff', like it should have a longer reach. I managed to get the 'trick' of gaining speed by falling on cliffs, but it still demanded 100% accuracy(then I played chicken mode and it was quite a breeze)...
Other than that, great graphics and music. I look forward for a 'sequel'! (or something along the lines, it's an intesting game conceptwise)