If you want to avoid the hassle just wait a month. No more issues with everyone trying to get in at the same time. And those with very short attention spans will have gone back to whatever they prefer.
I've tested 2/3 of the classes to at least level six and yes they all play fairly different. I'm enjoying it even though this Semi Open Beta is stressing the servers to the max. I've had ten times more CTD and server connection issues than the Closed Beta.
And if you're waiting for a highly anticipated MMO to have a smooth launch you'll be waiting a long long time. This game is great. I expect the first month or two to be a very bumpy start. Servers are not cheap they won't buy more than they think they'll need so the guess work is going to cause us all head-aches come launch.