I just tried to setup my new ReadyNAS Duo v2, but it did not go without a hitch.
At first I got presented with the setup process, after going to the IP address in my browser. At the end of the setup steps I hit "Apply", but got presents with a "Communication Error" message. After rebooting the NAS and playing with different answers for the setup questions, I decided to give up on the setup process by exiting.
Afterwards it turned out the password was still set to default. Trying to change it (logging out and restarting the browser) took many attempts, to finally find out it was caused by special characters in the password. In my case it was an "&" character, but I can imagine others might cause issues as well as well as special characters in other input fields.
I really hope this issue can be addressed, as I deem it to be a security weakening matter, not to mention quite annoying.
System: ReadyNAS Duo v2
Firmware: RAIDiator 5.3.5
OS: Ubuntu 12.10 (x64)
Browser: Firefox 12
Let me know if you need any more information or testing.