http://www.enspiar.com/dmdb/viewMission.php?id=494
Note the "version 0.9." There are some glaring issues I want help with, but being a newbie and not really knowing my way around, I wasn't sure who to ask and I thought it would be better to see if somebody would volunteer. ^^;
But as this is my first level set, I'm really not sure if I got the difficulty down for a Descent 1 mission. I've tried the levels out myself mostly on Hotshot, where they seemed a bit tougher than "First Strike," but still very feasible, but me being the creator probably means I'm too familiar with them to really judge. There are also a couple issues I couldn't seem to iron out with DLE-XP, one being a faulty secret in Level 5 and another being a load of bad cubes in the boss room, which is why I tried to keep the action away from that part of the room. The problems should be more obvious once you see them; I don't want to spoil too much here without anyone playing first.

But there is a .txt file included in the download that lists more of the issues. Some of them I couldn't seem to fix with DLE-XP and some of them are probably just my own mistakes, but ones which I don't really know how to fix. I hope it's not too much trouble.
EDIT 06.04.12: Version 1.1 has just been uploaded. All the bugs mentioned in the .txt file on the older versions are now fixed, and the mission is no longer just single player, but also co-op, supporting up to three players. The same link given above still works, so please take a look and try it out if you haven't already.
