Just to add to what people have already said about the Alton roads, I find the road my grandfather lives on to be exceptionally well maintained. It is a dead end gravel road with a fairly decent incline going up, so it's very prone to the washboard effect. As Rattlesnake Guy said, once that starts, it gets exponentially worse.
I was speaking with Ken (Alton Road Agent) a couple weeks ago and I believe he told me there was 6 miles of gravel roads in the town. I'm not sure how other towns compare but to me it seems Alton is above average as far as maintaining the roads.
The nice thing about gravel roads, is once they do get heaved up and rutted and banged around from bad winters, a quick scrape from the road grader turns the road back into great shape. Try that with a paved road, I know many paved roads in Alton that were beat up quite a bit from the past winter and it will take a while for them to get fixed.
I have to admit the road my grandfather's house is on sees very little traffic and I think that contributes to the condition. It honestly is better than paved roads for most of the year. In the winter it seems better as it doesn't seem as 'slippery' in adverse conditions.
I would certainly not hesitate to live on a gravel road in Alton, they keep them very well maintained. In fact, I will be moving up onto the same road I'm speaking of within the next couple years and am looking forward to being on a gravel road.
I also wouldn't worry about any vehicle issues unless your the type to be heavy on the foot over rough terrain.
Gravel vs. dirt there can be a big difference. No mud issues on a well drained gravel road but before his road was redone many years back, it was all regular dirt, you couldn't get up it in the spring time. Those years are gone though!