Speaking of levelling up, I had to reload a couple of times because I couldn't figure out how to get a second Zombrex, and I noticed that the perks you get upon levelling up seem somewhat random. The first time I reached level 4, I got an extra inventory slot, but the second time, I got a counterattack for when a zombie grabs you from behind. I'm now level 5, and still don't have that extra inventory slot. I wonder what this means for the full game. It would suck if the perks were random in that too.
Oh, and somebody mentioned earlier that the game crashed on them when a marketplace download finished. This also happened to me, so it's obviously a common problem. Also, I had some kind if glitch in the credits, where the models for all the objects (ie. anything that wasn't Chuck, Katey, the dead guy, or the background) were invisible. It was pretty surreal seeing Chuck and Katey pull up on an invisible motorbike, Chuck reach into an invisible truck, and then give Katey an invisible backpack.