I'm a big fan of bpython (especially bpython-curtsies), but I have to admit the multiline editing and the navigation keybindings in this are very nice. Bpython lets you rewrite the last line via ctrl-r but it doesn't let you navigate through a multiline function. I find the way bpython shows the docstring when you type the open paren for a method extremely useful, however, so that would be a nice addition here.

I used to use BPython. I really liked its way of presenting autocomplete. However, its scrolling drove me NUTS (it doesn't use your terminal's scroll). I was much happier when I switched to IPython.

Both are leagues better than the plain REPL, though. :)