+ Doing the bottom bit was nice and easy, while getting to the top was tricky. (+0.5)
+ I actually preferred the chaingun, since it was a nice incentive to move it through that area and not hang around, as opposed to a missile that would be easier to dodge and lead around. (+0.5)
+ Decent gold placement. All-gold is tricky as all heck, but there's some around for someone just trying for completion too. (+0.5)

- The chaingun area could have done with a small hidey-hole or two for breathers. (-0.5)
- The floor sweepers were nice, but seemed to be generally useless. The whole "flow over the ceiling" jump thing would have been better enforcable with mines, since it would mean having to stick to the ceiling a bit more strictly. (-0.5)

So, 2.5 + 1.5 - 1 for a score of 3.

bottom was really well designed, but the middle would have been so much better if you just put a missile there instead of the chaingun.