It can be pretty damaging to skin. I know most of the stores around here quit carrying it. I imagine because people may have gotten severe frostbite with it. You want to use gloves when you handle it.
As was already mentioned, it can build up CO2 in your tent or vehicle, so you have to make sure it is well ventilated. I personally think it would be more trouble that it is worth, unless you wanted to bring ice cream or were going to be out for a long time and wanted to keep some things frozen.