I commute every day on the Birmingham and Fazeley canal from Aston Science Park to Aston. I use a road bike with 23C wheels.
When I say every day, I tend to avoid wet days with puddles to avoid getting the bike too dirty, and light drizzle tends to make the bricks very slippy. Bike was seriously skittish this morning and a few scary moments, but no tumbles.
Biggest problem is the bridges - watch out for riders coming blind from the other direction. Don't forget to warn on your approach - I use bell and voice.
I suspect that the hard packed fine stuff has a tendancy to eat my chains, though.