Biggest one seems to be PC support.

What are the advantages over Airplay?

@chad_fullerton Airplay does full screen also so that's not an advantage. I purchased AirParrot and was very happy with it before AirPlay came to be. AirPlay (on Mavericks at least) completely replaced the product for me. For older MacBooks (no AirPlay support) and Windows AirParrot is the thing to have though.

@philfreo I didn't realize that they had added 'AirPlay Mirroring' as a feature. Back when I was using AirParrot that feature wasn't available with my Apple TV. I'm really excited now to mirror my Mac onto my TV. If that's the case, then you're completely right about it replacing the need for AirParrot.

Advantage over Airplay is that it broadcasts your entire screen. So you can load up your web browser or any apps you have open and put them on your screen. They don't have to be Apple compatible or from iTunes