I'm probably 2 years too late to be a useful answer, but NetApp NAS is far more than a bunch of disks!
Think of all the redundancy features you expect from a top notch SAN, and then appliy that to NAS file services.
All the disks are in double-parity raid groups, almost every component is duplicated, and the software offers rich features to assist with cross site duplication and management just to name two....
The new flash (SSD) arrays come with deduplication and compression enabled as standard, and are blindingly fast!
We serve Oracle databases and VMWare datastores over NFS, and although you do need to make sure your network has enough bandwidth, it's just as fast as FC. (We've got at 4 x 10GBps on some nodes and 2 x 40GBps connections on others!)
Add in the AutoSupport function which allows the NAS to effectively order it's own replacement disks when one fails, and it makes life very easy! Very nice function when you're managing 700 disks...