For almost two months I've been using a new computer. It's a mid-2013 Apple Macbook Air (MacbookAir6,1) running OS X 10.8.4. It has the optional 8 GiB RAM, 128 GiB SSD and an ANSI style keyboard. A friend who saw it said “Oh, it has one of those programmer's keyboards!”. As you can imagine, ANSI style keyboards are pretty rare in Sweden.
The computer is very fast, incredibly light and quiet. So far I've never even heard the fan. I've been travelling quite a lot this summer and it's been very comfortable to travel with the Air. It's like a luxary version of my Efika Smartbook but with a lot more oomph.
OS X itself feels very much like a real Unix. I feel right at home. That said, I mainly spend my time in Emacs or in ssh sessions to our development servers. Emacs with TRAMP (and a little help from rsync and ssh) works quite OK for remote development.
Here are some notes I wrote about what I've learned so far about OS X and how to configure it to my liking: OS X survival guide.