Overall great
Suffers from a few code errors though. The worst of which was in level 7. There is a part where you have to navigate through platforms that are going up and down, that are spiked on the bottom and can push you up into spikes above. It wouldn't be that difficult, but if you walk on one of the moving platforms, and it goes below the one that isn't moving, you tend to follow the moving one for a bit, which kills you. So I guess you need to work on collision boxes.
Other than that, I liked the way the shield didn't cover his whole body and you had to move it.
I think the bosses could have used some work. The difficulty seemed about right, but they were a little bit repetitive. Once you figure out the pattern, it feels like work.
Also, you should have been able to use the shield on the fireball boss.
Oh, and the combination bosses were a nice touch.