I have played it. It looks absolutely great, especially in motion - very, very fast und fluid.
But I got the impression that it's a bit harder than the PS2 edition.
Codemasters is bringing this and TOC Race Driver 2 (also known as DTM 2 or V8 Race Driver 2) to the European PSP launch - one of the best racers of this console generation in my opinion.
DTM2 looks great, too. The guys at Sumo Interactive that made the conversions for Codemasters do know their stuff. They are also responsible for Virtua Tennis PSP as far as I know.
By the way, TOCA2 will feature 12 players head to head via WiFi, downloadable Replays and a downloadable demo of the game for other PSP owners. Colin McRae 2005 plus will feature 8 players via WiFi and all the other stuff, too.