The towpath from Richmond to Teddington lock is currently unappealing and dangerous. These photos were taken in May and the path is a lot worse after in winter or after a spring tide.
It is sufficient for people on mountain bikes who do not mind getting muddy, but not easy for children, older people, less confident cyclists, pedestrians with buggies, cyclists on cargo bikes etc to navigate - basically all the vulnerable road users who would most benefit from avoiding the busy, fast moving traffic on the narrow winding Petersham Road.
I take this route to work and I have to plan for the fact that I will get covered in mud every morning, and take it very slowly because it is so bumpy. I have seen pedestrians and those with child buggies climbing over the flood wall and walking on the grass on Petersham field in order to avoid this path. When I have my child in the bike seat I get off and walk the section between Ham House and River Lane that is pictured as I don't feel safe.
With a bit of thought this path has the potential to be an excellent car-free cycling and walking route that would tempt people out of their traffic jammed cars on Petersham Road.
See also the discussion at http://www.cyclescape.org/threads/811