That was the historical part. Now construction part of the levels. I'll be much strict, so there may some information be missing...
1st map - Oh, what a blast. There's nice skybox that looks like a Moon relief or something like this... If the hole in ceiling was clipped, the rating of map should be 10/10, but this issue counts rating down by a half: 9.5/10 (still great)
2nd map - Much classic shaderlab textureset. Industrial theme is my rest of like while I'm an industrial child :D Conectivity is realy brilliant, 10/10
3rd map - Hmm, nice enemy territory as the textures are a bit industrialy and like alienbase based... I like the alien theme as well as war theme. There are few minor issues that don't count the rating much down... 9.5/10
4th map - Blood and scaring theme is the basic flag of Halloween... I like Halloween themed work a lot, minor issues conted rating down by one point from the ten: 9/10
5th map - Sock's architecture is amazing at all! This is total blast so rating isn't any other than 10/10
6th map - Geit is much unknown author for me, but his work has blasted my mind... Castle themed maps are nice and this is pretty nice map: 9/10
7th map - Most popular level played also on Quake Live as well... While ID Software likes this level I must say besides minor issue of positioning holdable item is this level briliant: 9.5/10
8th map - The last level of pack. From half empty level without the most important rune shit Guard is gameplay of level a bit boring. Theme is great, but there are couple of factors that haven't been much solved so it's counting the rating by three and half points: 6.5/10 (good level, but a bit boring)...
This pack is much of sort and IMO fully described including this additional comment.
So let's calc the rating of whole pack - (9.5+10+9.5+9+10+9+9.5+6.5)/8 = 9/10