the weapon sounds were better than doom3 :x 

There are a couple, I don't have time to dig them up now but check out 3dgamersedge.com for one, and the doom3world final maps section for a pretty cool level by Efx.

Q4 was exactly what it said is was going to be, a sequel to Q2, I still like the singleplayer in it. :) 

Q4 was good. I like the Strogg :) 

I had more fun in Q4 than I did in HL2, D3 or FEAR. 

yeah it did seem to get better and better as you progressed, I remember loving the fully upgraded nailgun weapon, it just destroyed everything in its path :)

Favourite levels include the nexus (??) level, the stroggification facility, and a few others near the start I cant remember the names of :(

Its just a shame the vehicle sections blew so much stomach contents in comparison 

Q4 singleplayer is average. i liked Prey a lot more. 

had some breathtaking moments thanks to really 'interesting' level design, but I found the combat extremely weak throughout most of it. Later levels redressed this to some extent, but for the most part I think it suffered from 'Doom 3 Imp' syndrome. I haven't had the urge to replay it, and I usually forget it was even released.