My drobo with all WD green drives is as silent as my Mac minis and MBP are, while a friend of mine has one also with similar drives that's so loud it's very difficult to sleep in the same room with it (and yes, it rivals his Mac Pro in terms of noise).
I've not had a single problem with my drobo since I got it almost two years ago, while others keep having them fail repeatedly and replaced repeatedly until they give up and find something else.
I've also come across people that think their drobo is great and infallible, and then go and realize they have no backup for the file they just deleted off their drobo. And come across people like me that back up their drobos because a drobo is purely redundant, which doesn't cover cases like accidentally deleting files off it and losing the drobo to fire/flood/theft and more, only situations like a dead hard drive or two.
I love my drobo to pieces and recommend it to anyone that wants a solution they don't have to manage...with the caveat that it's their data and therefore their responsibility to take care of it, and a drobo can only be one part of the solution. data robotics customer support definitely has a bad reputation that is probably warranted to an extent, but not many NAS manufacturers, nor you if you roll your own solution, can do much when things go very, very wrong with your device for whatever reason.
(Note that I use my drobo only as direct storage. The drobo NAS solutions always seemed a bit hacky to me...)