The rain was a pain but didn't ruin Mark Twain! Though I grew up outside of St. Louis, I'd never been to this campground or to Mark Twain Lake.  Really enjoyed exploring the area and the campground was nice.  Showers were a short walk and campsites had a decent amount of privacy.  The Loop we were on was really better suited to motor homes and we were tent camping.  We had two tents and had to set them up in kind of a odd location near the loop road. Some sites were better then others but I wouldn't come back to this exact site to pitch a tent. If you have a camper though, its great. 

You are right on the lake here, though it's a bluff so when you get to the edge, there is a steep drop off. It's very pretty and my kids are 9 and 11 so I wasn't worried but if there were much younger I'd be concerned about letting them wander toward the lake as they could slip and fall in.  Since part of the reason I take the kids camping is to be able to let them explore, I'd go to another area with younger kiddos. 

That being said, there was a trail that you could take for about 10 minutes that took you down to water level and is decent for swimming.

We took a day trip to Hannibal, which is a fun little town. Took in the Mark Twain Museum and took a riverboat cruise. On another day, we rented a pontoon boat to explore the lake, which I'd recommend as well. 

Once you get the to the campground, you are at least 30 minutes from any store, gas station, etc, to stock up.  

We were there mostly during the week and it was very quiet.  As it got closer to the weekend, it started to really fill up and get more lively. Mostly families and such so didn't mind but just a heads up. 

In the end, lovely area, really well maintained campground and would recommend.