I got to play both the Hawken and iRacing demo's today at their booth. First time using an Oculus as well! I'm familiar with Oculus (been watching this thread too), but never tried one.
First, I couldn't use the Oculus with my glasses at the demo.

The first time it seemed like it wouldn't fit with my glasses on, so I just took them off (I can still see ok without them; I'm farsighted as well which I'm not sure if that's better than nearsighed for the Rift). However the second demo guy said that he's pretty sure they'd fit, and I did get them on (very, very snug), but my lenses bumped up right against the Oculus lenses, and it was pretty blurry. From the little I know about Rift, I assume if I had this at home I'd probably be able to play with different lenses or something to get it to work. Hopefully the consumer version will be better in that regard.
Second, in terms of resolution it was pretty good, totally playable. I could read some small text in the iRacing demo which was neat. However it's definitely not perfect, so it wouldn't surprise me if they started working on an even higher-res model in a few years once the price of those ultra-HD screens come down in price.
Third, I was midly disappointed by the FOV at first. It was pretty damn good, don't get me wrong, but it does feel like you're wearing ski goggles or something. Again, room to improve, but after about 30 seconds you really don't give a shit.
Fourth, the weight of this is surprisingly good! Didn't feel as bulky as it looked in pictures.
Finally, there is some definite blurring that happens when you move your head. IIRC John Carmack brought up this point at Quakecon where he said that low-persistence screens make a huge difference, and if that blurring effect is the cause, then yes, he's totally correct. Not sure if they're going to improve that for the final model or not, but it was noticeable when you were moving your head around (more-so in the iRacing demo).
Alright, onto the demo impressions!
Hawken was... okay. I actually wasn't that blown away by it. Graphically nothing too impressive. They also had a terrible demo setup at the booth. They didn't reset the game or anything like that, so in my demo I only found one guy and killed him and didn't see anyone else for the rest of my demo. Whatever, I then decided to just walk around the city, look around the cockpit, and my favorite, jump-jetting up and looking down as I fell. This is an area where the developers really need to work on their camera effects. When I hit the ground in Hawken I just sorta stopped and created a crappy looking texture effect on the ground. It didn't "feel" like I was in a mech slamming into the ground from 50 feet up. For the time where I was fighting an enemy, there was no reason why I wouldn't be looking straight ahead anyway, so I just didn't feel like this game showed off its true potential. The rest of my group that got to play the demo's sort of agreed. It was cool this was playable, but it definitely wasn't the best game to show for it IMO.
iRacing was really cool. It wasn't playable and you were just in the driving seat and could look around everywhere, but it still did a great job showing off the Rift. You could look over in the rear view mirrors to see a car coming up at you, and I actually rotate around to see them coming up on you. There was a point in the demo where a car spun out in front of you that also looked pretty neat as you swerved out of the way. The best moment for me was at the end of the demo when you were just sitting there, and I decided to look down and my mind was blownnnn. There was a body where it felt like my body was! And arms were my mind thought my arms were! The illusion was slightly ruined because the Rift wasn't totally tight against my head, so there was light leaking in through the nose when I was looking down, but it still was just an awesome experience.
All in all, I'm pre-ordering the consumer version day 0.
Slightly related, but I also got to check out the Virtuix Omni (it wasn't playable due to liability reasons). It looked really neat. It was pretty noisy as he was running around on it though. He was playing HL2 and didn't seem to have any troubles moving around really, including jumping on top of cars, leaning sideways to shoot, and he was also really accurate with that gun. I entered into a raffle for it, hopefully I win.
Sixense was also there, but they weren't showing off the latest STEM product (they did have molds of it or something it looked like). They did use the last-gen wands for the Omni and it seemed to work well.
All in all, good stuff. Really excited to see some new VR companies popping up and getting lots of great recognition! Really excited for how this will evolve over the next few years.