If you spend any amount of time in the python shell IPython could probably make your experience better. Syntax highlighting, gaining access to shell commands, and tab completion are just a few of the small things it can do for you as a developer. On the more complex end, the things it can help mathematicians and scientists do is beyond my comprehension.
To be honest, IPython is not my default python shell just because of habit. After watching Fernando Pérez’s presentation at PyCon last week I was fascinated by what they are doing with the IPython Notebook. Its fiddle for IPython, with the ability to rerun snippets of code, and display inline graphical data in a browser. You can save you sessions, and easily run any portion of your code.
I can wait to play with it more and you should check out the presentation. The demo starts here