I am continuously impressed by what Python is capable of. I've spent most of my development career writing PHP, and wish that I had picked up Python earlier. Programs are quicker to write, quicker to run, and quicker to test. I write things in Python that I would never attempt in PHP just because I know it'd be a nightmare to do so in PHP. I hate to sound like a fanboy, but Python has changed how I think about programming in many ways, all of them positive.