It isn't a fearsome ride. The Isle of White is lumpy, particularly the run out from the ferry up to the Needles. The mainland is rolling rather than hilly.
There is a real sense of adventure on the route, it has some lovely and varied views all along the route. The novelty of a chain ferry (as well as a proper floating ferry) is a real experience.
I might do it, as it is a great ride. But I may still be recovering from the Raid Pyrenean.