This is a very pleasant way of seeing London - just sitting and watching the world go by or getting off at an attraction, then getting on another boat to continue the cruise. Only had one complaint in that at one stop they didn't announce where we were. Hence we missed the stop, and had to wait around for a boat back. As the tickets last all day this didn't spoil the trip at all though.
I would certainly go on this again and would recommend it to anyone.