Agreed, the first 6 weeks I rode on mine were not great fun, but I emerged fitter and tougher out of it. One of the big differences (as Gil points out) is that you have to work to maintain speed - but as a result you will hang on in corners rather than do 'comfort braking' and will get out of the saddle to kick it over small rises. At the end of a couple of months then you will be much quicker (on any bike) than you ever were.