I set it up yesterday, with 6 Hitachi Deskstar 5k3000 2TB disks, and set it to Raid 5 mode. This was done very fast, I was quite surprised, the NAS did the whole Raid 5 configuration in about 10 minutes.

I also started copying my stuff to it, still will need longer time until everything is copied, but so far I'm happy with the transfer rate, which stays constantly at 70MB/s. Only copying from my main disk was a bit painful, as that one is always spinning because torrents are up/downloading, and so I only got 10MB/s.

You can find all of the information about the QNAP TurboNAS TS-659 Pro II here.