Just posted: Canon Speedlite 600EX-RT Flash Review
I've been using Canon's newest flash system for over a year and can easily say that it is their best ever. The radio wireless control along with other improvements make the 600EX-RT a very solid upgrade from any EX flash kit including those utilizing the Canon Speedlite 580EX II.
B&H has the Speedlite 600EX-RT in stock. Buy the two flash plus transmitter kit and save over $100.00.