Short and sweet review: Buy it!
I've just spent what could have been the most boring night shift ever, saved by Mercury. Excellent graphics that make WipEout seem ordinary, good music, and psychosis-inducing gameplay! Move a blob of (physically very realistic)liquid metal from start to finish; sounds simple? It is. Or it would be if you didn't have to worry about colour changes, bits of your blob falling off the sides, ramps, conveyor belts and other weirdnesses!
This game is so good one of my colleagues (who has no interest in video gaming)is buying a PSP just to get it.