Gonna be honest; I've never been. But, if it's like what I think it is, it's probably got the amount of crime you'd expect. I know that it's not a terribly poor area, but it isn't rich. The several races probably get along decently, I knew a white guy who's brother moved there a couple years back, he likes it, but he is also kinda crazy. Windhoek and Walvis Bay are probably their main tourist destinations (and have a decent sized white population for an African city) so more than likely the people there are friendly, but being white and foreign they will probably assume that you're a tourist if you're planning to live there. And they can more than likely spot a tourist a mile away, so don't waste all your money on nic-nacs. Most places in southern Africa are generally easy going and laid back, Namibia probably isn't an exception to this. I've never heard anything bad about Namibia, so I'm going to assume it's relatively safe as a whole, but again, crime is probably what you expect, possibly mostly drug dealing and petty pick-pockets. I've read on the internet somewhere that the government is very strict on keeping up laws and that marijuana charges in Namibia can throw you in jail for a 20 year sentence, minimum. This leaves me with the only thing I haven't said anything about yet: Swakopmund. Swakopmund is the whitest part of Namibia, probably the safest area for whites in the country. I don't know what there is to see there, or how it is economically, but it is more than likely the best. I'd say you'd be fine visiting or living there, but I don't know why you'd want to live there but I'm sure you probably have some reasons. Good luck.
I really do hope this helps, keep in mind I've never been to Namibia, and I've based all my information from what I've read online, a combination of fact-sites and expat blogs.