NarNar, you're genuinely spoiling us!
Firstly, it's probably a good idea to upload your maps to Quaketastic. - http://www.quaketastic.com/
Secondly, I made you a demo - http://www.quaketastic.com/files/demos/5cat.zip
Now let's get down to the map!
You have improved a huge deal since your first map. The texture choice in this map is really interesting, although a little flat (it's good to have a couple of different colours in your theme). This could potentially not have been an issue if you had not used 'minlighting' which is setting a default light level in the world spawn entity. If you need a good 'fill light' then I would suggest using a light with a large range.
Try something like -
This should give you some decent results in filling a room with light but not having the "flatness" that comes with using minlight, also make sure you use it nearby a light-source.
I'm glad you took on-board everyones advice to create more open rooms rather than using lots of corridors, the gameplay was more fun in this map than all your other maps. There are still issues, room size is bigger than I would expect for so few enemies. I would encourage you to use monster patrols so that you don't always encounter the monsters in exactly the same place (this small difference can add an extra layer of re-playability to your maps).
Most of the rooms had the same floor height, you can make encounters more fun by having enemies on walk-ways or raised floors. Especially if you use rooms as big as yours it's a good idea to have this height variance.
Overall though it's a huge improvement and I hope you keep mapping!