If you drop your pandora from a small height, it's very likely that the bump causes the battery to briefly disconnect, which causes a reboot.
The battery cover has tabs that can break off relatively easily. I currently only have 1 of the 3 tabs left on it, but that still seems to be enough to keep the battery in place (although if I bump it too hard (e.g. putting it down on a table with some force), I get a reboot). Useful advice: don't remove the battery cover if you don't need to (I did remove it a couple of times just to show the battery to some people, and that's probably what killed those tabs - when I'm showing off, I'm probably less careful than usually, because then I want to remove and put back the battery cover as quickly as possible).
I have a black case and I have my Pandora less than a year (about 9 months now), but I use it quite intensively (I take it everywhere with me, nearly always without carrying case, just right into my pocket or backpack). It has had a few drops from small heights (< 1m) on relatively soft surfaces (wood, couch, carpet). Over this period of time, the two battery cover tabs broke off and the case got some cracks and scratches. None of the cracks feel like they're threatening the structural integrity of the case though. The cracks and scratches are barely noticeable from a distance; this is probably one of the advantages of matte black.
So conclusion: this is certainly not a resilient or ruggedized device, and it is probably less strong than big-company handhelds. It's not something extremely fragile either. If you treat it reasonably carefully, it will probably last quite a while without physically breaking.