You cant really comment on the levels since there is only 1 map to play at the moment.
As for lag i havnt noticed it at all and i have a good fps from a ok comp.
to be fair i think ET is a good addition to wolfy beats the crap out of Wolf Tactics which is just like unreal tournement and dosnt deserve the name wolf in it.
Wolfy is the only FPS that i can really play because the feel and look is just right. I feel the same when playing ET if it felt like other FPS like BF1942 or allied assault i just couldnt play it.
I think when the final release comes out it will live up to its name.