K Here we go:
Schools: You'll be moving up from #47 to #1 (depending on what you look at it could go to as low as #4 I suppose

). ND also tends to compete with Singapore and South Korea in math scores (you could say Japan is in the same division but they're perennial cellar dwellers). ND is usually number 1 among the states in the following percentages (I say usually because we sometimes slip to # 2 in HS grad rate - Those **** Iowans!

): 1. % of kids graduating High School 2. % of kids graduating from HS who go on to college 3. % of students entering College that actually graduate from college. I know Bismarck public schools outperform the state averages by a pretty significant margin and its likely Mandan public schools do to. So if you like math and college, the schools should be ok.
FYI Bismarck has significantly higher teacher salaries than Mandan and does better on test scores, graduation rates, etc. This isn't to say Mandan has bad public schools (they're quite good in comparison to the rest of the country) but it’s something to consider.
Friendliness: North Dakotans can be somewhat reserved at times but if you make the effort to break the ice they're a very friendly people. Also, Bismarck - Mandan is growing quite briskly of late which is good for friendliness since its been my experience that others who have also recently moved to a new place tend to be more open to friendship. If you're younger than 35 or 40, I also know Bismarck -Mandan has a farily active young professionals group which is usually a great way to meet people.
http://www.ypnetwork.org/
Housing: Bismarck-Mandan recently passed Fargo as the most expensive housing market in ND but it’s still cheaper than most places. A friend of mine recently moved to Bismarck from Charlotte and was a bit unpleasantly surprised by the local housing market. He was expecting it to be much cheaper than Charlotte - Prices were a little bit lower but not by a significant amount.
You may have already been here but here's the website for the Bis-Man Chamber:
www.bismarckmandan.com. The relocation section looks pretty useful. According to the living here section. Bismarck-Mandan is the 3rd safest metro in the country. I think that's good unless you enjoy being shot at and/or burglary.