I'm happy with my TF101 for now, maybe when Asus releases a high resolution tablet I'll be intrigued enough to dish out some cash. I may also be interested in a Windows 8 tablet when they release theirs... we'll see.
I have a TF101, awesome support from Asus, even released ICS for it. The Transformer Prime seems to have some hardware issues with WiFi and GPS, to the point where they no longer list GPS as a function of the device. I don't see the point of purchasing the 300 model though, other than it being a hardware fix for the issues with Prime. I'll also wait for the Infinity, bigger screen resolution could be a plus.