My parents have a camper parked on a seasonal lot at Yellowstone Park, that I recently stayed in.
My first impressions were "ok a normal run of the mill campground." However, after I met the owners and staff my impression started to shift. They were all so friendly and accommodating, everyday they were out in the park maintaining the lots and interacting with residents (all positive interactions).
The grounds are well manicured, the pool and surrounding area is nice, large kids playground, and very clean community bathroom/shower and laundry facilities (coin op).
The residents are all very nice, they wave and engage in friendly conversations. At night they party, but not loud and into the early morning, most times 😉.
I'd have to say, if you're looking for a temporary stay or a seasonal stay this is a conveniently located park 15 mins away from rt1 and wells beach or 5 mins away from stores in Sanford. And if you choose to stay in the park for the day, there's a bunch of nice people to hang out with.