Just tried this out last week. The docs are pretty sparse, but it seems to mirror the jQuery interface fairly closely so if you're familiar with one, you'll have a fair idea of the other: http://packages.python.org/pyquery/api.html

That's the key advantage as I see it. If I'm scraping something it's often in a hurry and I just want it done. Not having to internalise a new API is a significant win in that respect.