I had one and LOVED the side mount air. It is low profile and low current draw. We were staying in a remote campground that only had 20 amp circuits, we were the ONLY people with our air conditioner running that night and it was in the low 80's.
The only issues I have had is to make sure it drains properly. Marty G and I both had issues with our factory installs, there is an aluminum pan under the unit that needs to extend past the wall into the wall shroud and it needs to be well sealed to keep water out of the wall itself. Also when setting the trailer up make sure you are slightly off level with the A/C on the low side.