I have a desktop Windows machine that I'd drop in a heartbeat if I could get the same specs in a Macmini.
The Iris Pro graphics doesn't make up for the weaker dual-core designs. I'm not terribly fond of the Apple Laptop designs, as I feel they are overly compromised (eg the macmini 2012 is more capable than all the 2014 13' Retina Macbook Pro and Macbook Air's), versus the desktops which undoubtly beat the mini. That said, the lack of OS X on more capable desktop/laptop hardware is often a deciding factor in what Mac or PC someone buys. It's perfect for iOS development/cross-development (eg with monogame/xamarin) and is reasonably powerful enough and portable enough to be used as a HTPC or taken to convention settings when there is power available. The Mini is popular where you need a Mac but it's not your primary machine.
