I had one for about 3 months during the hottest times of AZ summer. Kept things "frozen" (ice cream/popsicles) they weren't hard, was on the borderline of melting but nothing liquefied, just soft. Keep in mind ambient temps were 105-115, vehicle interior temps probably 130+. Fridge ran constantly and a few times hit the low voltage cutoff after sitting for 2 days without starting the truck (3 batteries, diesel engine). Considering the extremes, it worked well.
Cons: The fridge is BIG and HEAVY. Not something you want to take in and out of your vehicle. Make sure you have clearance when mounted inside your vehicle to open the doors. The FM-62DZ seemed to be a power hog. I now use two ARB 50s and combined they don't draw as much power. I didn't like the interior, it seemed fragile. The interior side walls felt like the consistency of aluminum turkey pans, the top insulated doors sounded like hollow, thin plastic. Over time with foods banging around during offroad trips I'd think the interior would be beat to hell. Side carry handles are plastic using small screw hardware. Considering the weight of the fridge and if loaded up, the handles would eventually give out.
Just my 2 cents.