Works fine (I also used to have a Mini, and we get some 100+ F days in the summer around here too) - of course it is a fairly small cabin to cool. I find that tinting the windows helps quite a bit also.
Seat ventilation is a nice option too. Became available in 09. It only comes with auto climate control and the ventilation is not available on all seat choices. I'm in a tropical climate (Malaysia) and have an 09 Cayman with auto ac and the standard manual vented seats and have no complaints.
I live in Florida and I think that the ac is pretty good. I had a 335 before and thought that that ac was the AWEFUL. The best ac of any car I've ever had is my wife's G37. Even if it's 90 and humid you would still think that you're driving around in a meat locker. Truly amazing.
For some cars in the Middle East there is a GCC spec which increases the capacity or certain parts to cope with the heat but I don't think Porsche change anything and I've found even with temps of over 120F I've had no complaints with the AC on the CS....and the coolant temp never moves from the middle.