The Mk II version of the Canon 24-70mm f/2.8 has been very eagerly awaited, with rumours of its introduction being "imminent" dating back to early 2008 at least. Over 4 years later, here it is. So was the wait worthwhile?
Well, the two most immediate observations from many people are that [a] for some reason Canon didn't fit the lens with IS; and [b] it's surprisingly expensive. Neither of those are good things.
But those are probably the only two downsides. Tests show that this lens is sharp sharp sharp - better than the excellent 70-200mm f/2.8 L IS Mk II at 70mm, and better than every other Canon lens, including primes, at 24mm. That really is quite insane. This lens is so sharp wide open that you can just leave it at f/2.8 all day and forget about it, unless for artistic reasons you want the increased depth of field or slower shutter speed that a smaller aperture will give you.
It's built to the usual Canon "L" standard, of course, and it's a bit lighter than the Mk I lens it replaces, which is great news for photographers lugging it around all day long at weddings. It's going to be a very, very popular lens with professionals.