I agree and disagree. If you want high performance NAS like you'd get in a data center, then drobo definitely isn't the way to go, but if you are just looking for a simple home unit for backups and maybe storing media on, then it's not all that bad.
Think of it like an apple product, simple, elegant, streamlined, but still missing some of the advanced features you could get if you built your own.
Yes, the slow speed sucks, no, it doesn't affect streaming video / music to something like mythtv or itunes. The biggest PITA for me is that when it sleeps it takes a few seconds to wake up and spin up the disks.
I've had one for about a month and have no problem with it streaming video (divx) to my mythtv or having my mp3 collection on it for itunes, or storing all my pictures on it and accessing it from lightroom. I chose it because I had gone the "build your own" before using linux + lvm + evms + raid and decided I wanted something I didn't have to maintain or worry about. YMMV of course, depending on what you're looking for
Living on Earth may be expensive, but it includes an annual free trip around the Sun.