I love my 650 wheels - or more precisely the bike they are on. It sold it to me when a frame designer said "I design the frame to fit the person - then I see what wheels will fit. If the person is under 5'2", 700c wheels never fit without adjusting the frame geometry". Frames which will fit a 5'1" person which take 700c wheels are a bit of a compromise. You tend to get a very steep seat tube & a very slack head tube (as well as toe clip overlap. In addition, the bike proportions look a bit odd as the back wheel is higher than the top tube. Disadvantages of 650c wheels are less choice in wheels (& to some extent tyres) - but fit is king & in my mind vastly outweighs all the other issues. If you are 5'4" then you are on the cusp. Note the discussions by really tall blokes - they have issues w/ 700c wheels because they are too small for their needs.