I just wrote a really long reply to this and IE fucked up when I tried to post it and lost it, so I'm just going to say FUUUUUUUUUUUUUUUUUUUUUUUUUUCK!!!!!!!!!!! until I calm down enough to write it all again and re post.
EDIT:
20 years ago 40K was an interesting sci fi setting with lots of potential. Now it seems to be a marketing machine designed to sell little bits of plastic to teenagers. That said, it certainly looks like there's the potential for a vaguely sensible sci fi universe in there somewhere. The bits of fluff I have read recently don't seem to have been too over the top, so maybe it's just the teenage fanboys that make it seem stupid.*
I played 1st edition 40K for a bit and stopped just before the change from a more adult oriented product to the one that was meant to appeal to teenagers, around about 1993. I played a few spin off such as Space Hulk and Epic as well. A couple of years later I got into Warhammer Fantasy Roleplay V1, and since then I've preferred Warhammer Fantasy to 40K. The fantasy world is a lot better realised IMO and I find RPG's more compelling than tabletop wargames.
I forgot about warhammer and 40K until 2007, when I found DoW and Warhammer FRP v2 had come out. Since then I've got back into it a bit, having it all computer generated rather than having to bother with painting and dice is great.
I played DoW a lot and DoW II was fun single player, but unfortunately had no longevity. Fire Warrior was also crap, as was Warhammer Mark of Chaos. I would have played WAR except for the monthly fees. I would really like to see a 40K game that mixed elements of RTS and TBS, like DoW, Galactic CIV, Sins of a solar empire, Total War etc. Space Battles, land battles and resource management. It would involve conquering a new sector of the galaxy for the Imperium (or whoever). It would be awesome.
WHFRPV2 was/is great and I was happy to hear of Dark Heresy being released, I even bought the limited edition rulebook as well as all the extras and all the Rogue Trader books, but I can't really get myself interested in the 40K universe on a personal roleplaying level. The battlefield has been covered in great detail but the social fabric of the Imperium and it's ordinary citizens hasn't really been given enough coverage to get into it. I also dislike the system. I liked it in WHFRP, but they took all the bits I didn't like about it and expanded them for DH and RT.
I still have a large army from 1st edition as well as a few bits for Space hulk and other bits I did just for fun lying around in my parents loft as well as a good few unpainted ones, but I have recently bought a few new mini's and painted them in my spare time as an alternative to games (and at the moment a ladyfriend, dammit) but I'm not interested in playing the game again.
Right, here goes with posting, it had better not fuck up again...
EDIT2: Hooray! and *Also, I ignore some of the more recent developments like the Tau, Necrons and Dark Eldar.