In my experience with other OS' (Windows 3.1 -> Windows 8, Ubuntu 4 -> Ubuntu 13, half a dozen other Linux varieties), I've never been able to open the box and get to work within half an hour. There's always been some niggle. It's a bit trickier now that the dev tools are an optional download rather than a CD/setup option, but in practise I'm usually good to start working with a fresh Mac in about half an hour. With Linux there's a lot more tinkering to get it just so, and with Windows there's generally a lot more to download and configure to get it working comfortably.