I used one on Blueberry in the summer, however it no longer fits her!
Really depends on the bunny, and they walk you! Blue was happy to let me put the harness on her which is the first obsticle! then I let her lead me round the garden, you have to make sure you keep up if they suddenly run as you don't want to pull on them.
I'm sure I posted some pics before have to see if I can find the thread.