F1Fanatic has a post up with visual comparisons of the seven (arguably eight) cars announced so far.While the Red Bull is the most visually interesting so far, just about all the cars have interesting elements.
It is also apparent to me that the shark fin on the back of the cars will probably be a circuit-specific modification for some teams; while the Toyota was unveiled with only a small fin, its first public test showed it running a much more pronounced fin.
