I'm a happy Drobo user. Had one for at least 4-5 months now (maybe longer, I don't remember). I purchased 4 500gb drives, and total to my door cost was about 1k.
Installation: click the drives in. Install the software (optional but reccomended). Plug in.
A monkey could do it, so I was able to manage
Since then, here are all the errors and issues I've encountered:
Really, it's that easy.
Downsides: Slow. But considering it's a mirror of another fast drive, it's only purpose is to not die.
I use Syncback to create a "watch folder", so that as I ingest any images, I automatically have a backup. Once I caption, edit, and more or less add the fine details to my work, I can move it to a proper folder on my main drive, and mirror that to Drobo.
Drobo is proprietary, but RAID's aren't exactly easy to deal with. Considering the lack of maintenance I've had to do in the last 5 months, I'm quite happy with the unit. I've had many more problems with my desktop or laptop in comparison, and if I had to bill myself for time lost or hire someone to fix it (though I am technically proficient), I would have made up for the premium paid on the Drobo easily.
If anyone has any questions, please let me know.
I'm currently storing over 800 gigs on there.