I got my copy at EB yesterday. There were a couple of people in line and one bastard tried to get it, but didn't have a pre-order, so he wasted our time.
Anyways, the game fucking rocks. It's laggy on my computer at the lowest possible quality, but it's still a lot of fun. It's freaky as hell, too. It was exciting when the Pinky Demon first appears; he jumped off of a balcony and started headbutting a steel door, making a huge dent in it, and then he gave up and just jumped through the damn window... The Shotguys are bastards, too.
I tried to Deathmatch on a server, but it was so bad that I could barely move. Everyone got pissed and the server shut down.
The detail is amazing. And not just graphically, either. I'm also talking about the level design. How many people were freaked out when that Imp jumped out of the staircase in the beginning of the game?

I noticed a couple of glitches in the game as well, so I started posting them on my blog. There were three so far, none of them too big, I suppose
What really spooks me is when everything turns blood red for a while and monsters start jumping out of walls and ceilings. The cutscenes are really good.
One thing that made me run out of a room was hearing a toilet flush by itself in a bathroom

Finally, look in the instruction booklet. There are things labeled "Tip" and "Doom 3 Lore". The latter tells some interesting facts about the game and of id Software. Also be sure to read the note on the back of the keyboard reference if you haven't already done so

This is one hell of a game.
Edit: Reduced the number of emoticons