Looking for feedback from other owners. I have found with my 51 if I don't pre-load it with food and pre-cool it at least 24 hours in advanced with 48 hours being better it does not hold the temperature across the fridge very well. I have a dual temperature thermometer with probes to better keep track of the actual temps. On this past weekend trip the dairy section was way too warm and the main section was a bit too warm as well. The fridge was set at 32 with temps in the main area around 40 and the dairy fridge at 60. On the morning of day 3 everything was great. Main area was 30ish and dairy was 40ish. The fridge was in my truck and briefly pre-cooled without food prior to loading up at the grocery store. My other main complaint is if I have the fridge at 30 and it reads 32 the fridge does not kick on to cool down to 30. I have to set the fridge, at least temporarily, at 28 to kick on. 
Here are my brief pros and cons compared to my 37 quart ARB which I sold to get a larger fridge. I have owned this fridge for about 6 months. 
Pros:
Price point - Way more budget friendly than the ARB. (Some will say you get what you pay for)
Dimensions - It is skinier than the ARB so it makes it easy to fit more gear in the back of my FJ (also a con)
Deep Dairy area - Large bottles fit easily here to save room for food in the main sections (see temp issues below)
Draw slide - Excellent quality, no issues, and reasonable price point (especially when on sale)
Cons:
Dimensions - The ARB is a wider fridge and the space just seems more efficient. On my 37 qt you can fit a dozen eggs width wise in the dairy area. You can't do this without splitting a carton of eggs 
Temperature control - The fridge seems to like to have a 4 degree temp delta before turning back on. So if you have the fridge at 30 and it climbs to 32 the fridge will not kick on until it goes to 36 or you lower the temp to 28. I am having a harder time finding a sweet spot temperature on this fridge compared to my ARB to keep a few things at the bottom frozen and then rest cold. 
Lid - Isn't as rugged as the ARB but I haven't had any issues to date
Dairy Area - While being much deeper than the ARB in theory is great. Unless you have the fridge at below freezing this area can be as much as 20 degrees warmer than the main section. On the ARB is was 10 or less. It is great for large sports drink bottles, juice, etc but it is best if that stuff is already cold and the fridge has been pre-cooled. 
Hope this helps new and future buyers and I hope to hear what others have experienced. Mine is wired to 10 awg wire to a fuseblock with a deep cycle battery. Never had any issues in those areas.