To clear up the air a bit... Yes, the client they used in the PVP weekend was a stripped down version of the actual game client, and was a few versions behind the actual game build. The purpose was the try and make the game as light as possible so it could be easily distributed (though from what I hear that didn't go as planned for most lol). As far as the laggy and unstable part, I found the client to be extreamly stable, though not very optimized. Obviously since its a few version behind and stripped down I assume the actual release version will be a lot better in this department. As far as lag, my latency bar was always green, and I think what most people persieved as lag was actually game stuttering, caused by the large amount of people in 1 place and, again, a lack in optimization.
I think all the above put together is what made all the kiddies whine on the gamespot forums. I assume they were all just looking for a free ride into AoC, and what they got was a beta test (which really is what it was). To be honest I am glad those people won't be playing, as it will make my gaming experience a lot better. I didn't experience one thing in the PVP event that I tought couldn't be fixed easily by launch day, and it was enough for me to finally pre order the game. If any of you are interested in some solid reviews and class experiences, you should head over to the AoC official forums as it's full of posts on the subject.