Drobo is not reliable
I'm a first generation Drobo user for about three months. I've used it as a back up solution, and to store my Aperture library. It does setup easily, and even the first generation unit (USB2 only) was usable for Aperture. Yes, it is a little slow, especially for video.
My main issue with it is that only three months after installing it, I lost everything on it. Data Robotics support was slow, and largely clueless, only repeatedly asking me to reboot the unit, and send diagnostic files.
Unfortunately, the unit died in such a way that the Dashboard (the software used to monitor it) couldn't connect, and therefore couldn't generate a diagnostic.
Two weeks after reporting the issue, they gave up.
If you do buy one, be sure to maintain a good backup strategy, and copy everything on the unit somewhere else.