On my Windows 7 machine, they're really ugly (in IE, FF, Chrome and Safari). I double checked to make sure ClearType was enabled, and it is.
I don't think I'd use any of these in a project where I needed a polished look and feel.
I much prefer Smashing Magazine's non-Google font-ified header font.
Kudos to Google for taking on this project, though. As others have said, this could be a catalyst in getting the foundries to open up their fonts to the web.
Chrome, Firefox and Safari all render beautifully on my machine, with Safari experiencing some rendering errors; Firefox even does ligatures correctly, which is something I've had trouble with before with fontsquirrel and the like. Whereas on my Ubuntu box everything is sharp and jagged and ugly as sin, particularly in text sizes like 14 and 12 pt. I'm inclined to think that this may be a font rendering issue, like the known tendency for ClearType to cram everything to a pixel grid.
I don't think I'd use any of these in a project where I needed a polished look and feel.
I much prefer Smashing Magazine's non-Google font-ified header font.
Kudos to Google for taking on this project, though. As others have said, this could be a catalyst in getting the foundries to open up their fonts to the web.