i'd like to add a serious plus one here. this computer is awesome - coming from a 2008 mbp in particular. it's half the thickness and weight, the screen is gorgeous, and the hard drive is fast. yes, i can't upgrade the memory in a few years - which is why i got the 16gb now. yes, there is an occasional hiccup with graphics scaling and non-retinized apps - but it really isn't half as bad as the people on here complain about. and yes, it was expensive - but it's also completely worth it, to me.
in short, great laptop, and totally in line with the 4/5, A-, etc. type of reviews that it's getting.