I've had this thing since Monday, when I fooled myself into thinking that a year of fileplanet for $39 is not that bad of a deal and I might get some decent use out of it. But basically I got it because QW is the only game left that I was really, really looking forward to. I'm a hardcore fps vet so keep that in mind as you read my impressions.
ETQW very much follows in the vein of RTCW/ET's mix of fast action in a team based, tactical shooter setting. No, it's not nearly as fast as Q3 like some CS/BF nublets will have you believe, it feels very much like ET. The spawn-to-action time is generally faster on the map included in the beta due to the attacking team gaining up to three spawn points along the way as they capture objectives. Also, vehicles are almost always available even in full 12vs12 battles, so you'll spend a lot of time shooting.
Generally speaking, the game design is outstanding. All classes have unique and important roles, loaded with their own gadgets. Vehicles are useful, but not overpowered (I never felt the BF-like urge to camp the tank/plane to harvest ridiculous 20-1 K:D ratios with any of the vehicles in QW). The map is intricate and flows well. Firefights require skill in both aim and movement, and there are few quick kills that turn the likes of BF into "who sees who first" affairs.
What kills this game is not the theory, it's the execution, and I place the blame squarely on the Doom 3 engine. Like the good thing that you take for granted until it's gone, the sturdy Quake 3 engine with its silky smooth feel and netcode is very sorely missed. Firefights in QW have a real wishy-washy feel to them that would take several paragraphs to fully describe, but if you've played Doom 3 MP you'll know what I mean. It's a world of a difference from Q3 engine games.
This extends to vehicles, which to be honest are not at all meaningfully implemented at this point. Part of the reason why they're always available as I mentioned above is simply that they don't add too much to the game besides quick transportation. You can drive them quickly, but they have a very floaty feel to them, combined with a cockpit view that shakes way too violently whenever you're driving on rough terrain (most of the time), combined with netcode that at 100 ping made the faster moving vehicles often realign and jerk around when I drove them. Also, the tank/walker cannons are disappointingly point-and-click straight shooters, unlike say the BF1942 tanks where projectiles had an arc that proficient drivers needed to account for.
Lastly, I was disappointed with the only map in the beta. While it's definitely a quality map, it just doesn't have the wow factor that the incredible beach map from the rtcw test had. You'd think they would include the very best they have, but if this is it, it's not looking good.
Overall I've found QW to be a decent game so far that has a lot of potential that will never be fulfilled due to technical challenges. This is not the game that will resurrect the fast paced online FPS subgenre, and it's a real shame.