I've lived at sun prairie for the last 8 months and found you get what you pay for. It is fairly cheap (as compared to apt. complexes of equal quality in DSM), but still a good place to live for a starting family, recent grad, or college student.
A few things I dislike,
1) The rooms can be cold at times during the winter, and there is a bit of a draft when it gets really cold and windy out side (when it gets below negative 15 or so).
2) When I first moved in to my apartment, there were a few things which were broken. The microwave didn't work, and the mail box didn't open.
A few of the good things include,
1) The maintenance! It is very fast, they generally follow through with requests within the first day.
2) Snow removal is very fast, generally within 12-24 hours, everything is clear.
3) The office staff is very nice, and they always answer the phone right away when you call. They are very patient, and helpful.
4) Parking! There is a lot of it, there are probably 4 spaces for every tenant. The lot is never full.
To sum it up, generally everything is in good working order, there is hot water, cold A/C in the summer, good heat in the winter. There are no bugs, and it is a pretty nice living environment. No crazy parties, or people who are obnoxiously loud at unreasonable hours. I would give the apartment complex as a whole a 3.6 as a whole, but figured I would round up to 4, just for kicks.
Hope you found this review helpful,