I would definitely say YES. I upgraded my wife's MBP and she absolutely loves it. Everything runs faster. For my personal experience, and not my wife's anecdotal, there is a world of difference between running Photoshop on my Air with 4 gig and on any other computer with a comparable CPU and 16 gig.
As far as CPU speed is concerned, it's not quite as critical. I bought the second from the top CPU speed for my Air and I'm quite happy. I definitely agree with the comments about not buying the Retina display, they're much harder to service. I love my Air, but when it comes time to replace it in a few years I'll be getting another MBP and buying more RAM from Crucial to upgrade it.