A'right.
You want a deconstruction, I think I'mma give you one then.
It looks like you're motion tweening your 'stick man'. Don't. For a stick figure that's the worst thing you can do. Simply do him frame by frame. Not the easiest thing in the world, but neither is it the hardest.
The background wasn't too flashy, but I think it suited the stick man's style. Otherwise, you're great at background design.
The only problem I had was the rock. Not the fact the it crushed him, but the speed in which it did so. To my eye's it looked alittle... jumpy(?), but that could just be me. However, the stickman 'fell over' when he got crushed. A rock like that would just smash your body into the floor. All you should see is a river of blood.
You had sounds, you had music. No tips needed there.
Just practise is my last tip. Try new things, it really helps. You should try animating shomething really hard for about a week or two weeks. Then come back to this stickman. It'll be a piece of pizzle.
~L.A.B