I have a Drobo v2 and like it. It houses all my iTunes music and other media.
I can read about 2 GB/min off of it (34 MB/sec), which for me is plenty fast. I usually download from iTunes directly to the Drobo, so write speeds aren't as important, b/c the bottleneck is my ISP, not the Drobo interface.
I had Synology CS407 before, and while it was nice, it wasn't HFS+, and was limiting some things I wanted to do. Since I had a Mac Mini already connected to the home theatre, I wanted a DAS (Direct Attached Storage) instead of a NAS again, and this way I can use Slink or MobileMe to jump back quite easily to get anything I might want.