Absorption fridges work well though they are not very efficient. Most caravans use them because they are silent, and lighter in weight than the more efficient compressor fridges. Cheap cool boxes use the peltier effect and are even less efficient.
Gas absobtion fridges are fine for caravans, but not really for offshore boats. Thats not to say before small compressor fridges, lots of boats had them, including mine!
They were the only portable fridges around, still made now, still in use on a couple of boats I know.
Fine for the canals or river boats, normally a lot cheaper then compressor fridges.
Just as an aside, when in Cyprus with the UN, we had paraffin absorption fridges, big ones and they were great!