The intro sequence was well done, though I didn't notice any musical change between the scenes until the sudden change at the keypad entry part.
Shrimp level was probably a bit too brutal, those lasers! I'm not sure what I did to beat it, maybe just lucky in avoiding the lasers. I didn't feel like there was a noticeable use of adaptive music on this stage.
I liked the vertical cloud level and this is where the adaptive music really comes in, with the layering of the parts as I ascended. It was a nice progression. I think fading in the parts would work to smooth it out a bit as I noticed some rough edges but overall very nice!
Also I really dig the hand drawn art style, it lends a lot of great character!