I have one similar !
I can not begin to count the number of times it has come in handy. The air compressor alone has been a wonderful feature for low tires or inflatables.
You can plug it in where a/c is available and it will give you 12 volts forever. Without shore power a/c it will still power my O2Kool fan all night and my 12 volt lights off and on as needed. However, the a/c converter side is limited to about 4-5 hours powering a tv or DVD player. Then it does into automatic shut down to protect the battery.
I am well into my 3rd build and while I will have a/c outlets I am leaning towards all dc lighting this time. By installing a double pole double throw switch I can supply DC power from an onboard battery or an a/c to d/c power supply. I can live without tv and music and I can replace all cooking appliance with a good campfire but I truely hate stumbling around in the dark looking for this and that and a flashlight is the single most frustrating thing to be feeling around for in the dark. You know that flashlight the one with the almost dead battery that has about 1/2 of a candlepower dimmly glowing bulb.