Oh boy, that's a pretty cool Terraria level! I enjoyed a bit of much, thought I didn't like how the placement was, there was too many emenies, especially in the second section. There are also the ones that are difficult to kill or avoid, at least the level wasn't long. The atmosphere was okay, the SMW purple(?) pipe kinda bothers me, since it should be darker. I don't see anything wrong with the music, so it looks okay.
For the level design... probably okay. The first two warps should be switched to Instant button instead of Pipe because I don't see any pipe there. Also in the 3rd section there's a key which unlocks the door in the same section, which leads to a bland somekind bonus section, including 2 hammer suits... I think this looks pointless and it should be removed, unless you hide the key in some secret. As for gameplay, it is quite difficult, but I don't it's that bad. The boss battle was pretty good and not that hard and I actually liked it.
I think that's pretty much it. Overall - the level is good, but it could be better if it you put more creative effort of it and remove less emenies.