My only insulation in the ceiling and walls is thin, factory-installed bubble wrap. Its isn't really that good. If I was more motivated, or to do over again, the best way is to remove the walls like most do on here and put in good, thick insulation. I'm sure its night and day compared to what I have.
But I do pretty well with my foam floor, factory insulation, and the Dickinson propane heater. I also put bubble wrap over the windows in the winter, as well as cover the two roof vents with a sheet or two of Reflectix insulation. I have a large blanket that is velcro'd over the back barn door that keeps draft from coming in there as well.
As for the floor, I love the texture and warmth of the foam tiles. Wouldn't have a trailer or camper without it now. Easy to clean. Soft to walk on. Holds in some heat (or keeps out some cold).