I had a home built WHS. It did the job but was very much built for Windows as the client OS. I also couldn't do TM backups as it didn't support it. I did however set it up to stream music by putting my music on it and installing Firefly.
I have now got the Synology DS-409 which can do native TM backups, be an iTunes server and has got 2 iPhone apps for music and pictures. It also has good remote access features. It's small, quiet and tbh probably the best bit of kit I have got in a while (along with my Apple gear as well)
When looking at which NAS to have, it was a choice between the QNAP, Synology, Drobo, HP Home Server and Netgear ReadyNAS.
Decided on the Synology as the for me the HP and Netgear ReadyNAS were too expensive and the Synology has a feature that the QNAP didn't.
I've stuck 2x2TB WD Enterprise Class drives in there and have a RAID1 to protect. I am looking to get another drive tho as they will be full soon.