Doom III XBox,Co-Op online, ***great game*** Options

[Riel]

I played the PC version and loved it,never finished the game because it gets really hard later on and i just used God mode.

Co-op sounded like fun as well.I have to say that Vicarious Vision made an outstanding job on this...it looks amazing and runs at a steady 30fps,it looks better then Riddick on the XBox,you can save anywhere,there's even a quicksave button,the controller works really well...there's a little more loading then in the PC version,but it's not that bad and the loading screen is about 10 seconds.

I got to play some Co-op and it's a great ride...it's most of the single player game but with someone along...they added a few darker area's where someone absolutly needs to use the flashlight so it's very tense in some area.The 4 player Deathmatches and the like are very fast though but it's still fun i thought.

I'll be online with this most of the rest of the week so if you feel like playing online,the co-op especially,send a message.This game is at least worth a rental just to experience this mode alone.

[unitself]

So, I picked up Doom 3 for the Xbox a few days ago and I have to say - I really like it. It's great fun and genuinely spooky. I think that the "so dark that you can't see anything without a flashlight" are very cool. Those guys did a great job of making the flashlight look totally realistic and I love the ominous, claustrophobic feeling it gives.
I am so glad that I (finally) bought this game. It's just what I needed. Sometimes you just want to shoot hell's minions, you know?

Questions:
1. How long is this game? How many hours to complete for an average player?
2. How is the expansion pack? Fun? Worth it?

I haven't tried co-op mode online because I don't have a LIVE account.