Don't have any experience but from what i hear they are pretty handy if you don't want to invest in a full kegging setup. You have to keep buying the pressure bags or modify it yourself to use the small CO2 tanks.
I used one for a while till I got the keg setup together. Only problems I had were getting it pressurized and getting the bag out. Took up too much room in the fridge a few times, but just drank it quicker.