28 2.8 IS?
Not really seeing anyone buy this left and right. Nor its wider cousin the 24 2.8 IS. Nor even the 35 2 IS for that matter. There don't even seem to be any sample picture threads started in the samples forum. Though they haven't been out for a year yet, there have been no price drops and no one seems to be saying holy ****, its worth it.
Indeed, the 24mm and 28mm 2.8 IS could be worth it if they were at least as good - or better than the 24-70II, but they are not.
Perhaps they will develop a certain following with videographers, but to me those lenses are a missed opportunity. Had they been f/2 and with a proper short MFD, they could have been a very good alternative to some of the L primes or a good upgrade to the 28mm f/1.8, but at f/2.8, even with IS, it doesn't really add much.