I'm a bit late to the party in actually building a beta ArduCopter kit, but I just finished last night, loaded the code and set the motor rotation directions this morn. Then the kids and I took it out to our tiny backyard and just took off. This is the result--amazing. Rock-sold stability (this was in windy conditions, too) and no tuning required--these are the default settings. So much better than the Gaui 330 XS, both in terms of performance and setup!
Ted Carancho's configurator software is the key. Best setup experience I've ever had. It not only tests all your hardware, but really walks you through the process in an intuitive way. It looks great, too:
My only issue was the the rudder channel seemed reversed in the configurator, but worked fine on the quad. I'll dig into that a bit more. But the main point is this: ArduCopter is in great shape, and as far as I can tell, ready for prime time. Really looking forward to the commercial release in a few weeks. Huge congrats to the team!