I haven't heard of any DOWNSIDES as of yet, but I can tell you a great advantage.
StreamMyGame.com works with it. In case you're not "in the know" about streammygame.com, it's a service that allows you to effectively "stream your games" to lower-end PCs and play them. You can stream your Windows games to your PS3, such as Halo/Halo 2, BioShock, the (horrible) PC port of Gears of War, etc. You might need a USB keyboard, though. I don't have a PS3, so I haven't actually USED streammygame.com on one.