There is one point in Steve's review that is not quite right.
You do not need the new Canon flash to obtain E-TTL II. The difference between E-TTL and E-TTL II is internal to the camera and not the flashes. All of the Canon EX flashes operate with E-TTL II.
I own two 550EX flashes. I have no intent to sell them. They are great flashes.
Otherwise, an excellent review, BTW.
I just didn;t want anyone with EX series flashes to be concerned that they needed to replace them just to take advantage of E-TTL II. There is no need.