Short answer – very happy with my QNAP.
I had a lower cost NAS and it was OK but lacked features, speed and support so after some research ended up blowing my budget on a QNAP TS239ProII, mainly to get the fastest network transfer speeds I could afford.
Great bit of kit, really stable, fast and full of features, should you need them. Easy RAID configuration, on-the-fly expansion and easy backup via USB. Loads of built in server capability too.
RAID 1 – is worth having but don’t rely on this for backup. It’ll protect against drive failure only, not deletion, corruption or over-writing. I recommend you get an external USB drive for backups as well. Having suffered both drive failure and massive data loss at seperate times before, I now backup over USB regularly (QNAP will do this automatically as soon as a drive is connected, or can be set to do certain folders on a button push), then back that USB drive up again to another removeable drive every now and again.