I received a Munchkin Nappy Disposal System from The Soup to trial and I was impressed!
It holds the same amount of nappies as a shopping bag, as I discovered by emptying a munchkin bags into one, and it does reduce the odour significantly.
The system works by twisting the top of the bag when the lid is shut, and sprinkling baking soda into the bag as well. Unlike some other NDS the nappies all remain in the bag which you then clip shut and remove, rather than ending up with a “sausage roll”.
Personally I found the replacement bag price a little steep, but I am assured it is comparative with other Systems (expensive when viewed against my free shopping bags). However it is possible to hack the system to use other cheaper bags (by chopping the bottom off one of the “real” bags and placing the cheaper bag inside of it. I really like that you can refill the baking soda dispenser, which screws into the lap, with any old baking soda you get from the shop.
I really like this system and would probably use it if my change table was not set up in the laundry. I only have room for one bin (the Munchkin is approx the same size as a regular kitchen bin) and I find myself wanting to put lots of other stuff in it (like lint, plastic wrapping, price tags) which just seemed like a waste.
If you are going to use a Nappy Disposal System, then I would definitely recommend this one.