Multiplayer is pretty good, grab the demo from fileplanet and patch it to 1.07 (it might be a patched version there anyway). Netcode is much better now (their original "it's not the netcode it's the servers" argument turned out to be false, it WAS the netcode so they fixed it). Graphics aren't great, I'd say CS quality at least. The vehicles are tons of fun and don't effect the balance much (although a properly implimented light tank / heavy artillery or medium tank / mamoth tank blockade is a beautiful thing that will keep the enemy from getting too close to you with their vehicles).
Supposidly they're adding two flying vehicles per side to the maps after a couple of weeks. But you'd have to take westwoods word for that. I'd suggest just to play the demo until they actually release the patch for the full version to add the flying vehicles.
My only complaint about the demo is that it uses gamespy arcade, which is horrid at playermatching. Apparently the westwood online service is much better, but it's full version only, so I've never used it.
Edit : If you have a voodoo graphics card, don't even bother. It won't hardly work.