NVDA screen reader

Has anyone used NVDA? If yes, I would like to know your thoughts on it, vs. JAWS or Window Eyes.

NVDA (Non Visual Desktop Access) is a screen reader (free and open source) for Windows XP/Vista. I heard about NVDA from The Paciello Group blog, and wondered if others have used it.

I installed it, found it easy to use, and used it to test a few of my client sites with Firefox.