If you like a super light bike and lived in a cramped apartment you will love fixed. After owning a Trek Navigator for a while I practically threw my Langster up in the air after trying to lift it. It has to weigh atleast 15 lbs less!
If you are wondering whether or not to buy one and don't want to spend a crap load of cash I hear you brother. See my other recent thread on the Langster. For around $400 you can own a fixie that will give you a bigger hard on than a case of Viagra.
As for speed - this thing is pure torque. Ever see that tech demo movie for the upcoming x-box video game, "Rallisport Challenge 2"? The music and insanity of that is what I think of when I ride this bike. I can't wait to go down a hill on this thing on the drops. Oh dear god help me now..