As far as I know, the Galileo is the only maker-friendly SBC that has real WiFi support thanks to PCIe. That's a huge asset. On top of that, once you have a good bitbake environment set up, making custom kernels for it is a snap, and very satisfying to play around with.
I think the Galileo is a poor fit for an Arduino platform, but it excels as a competitor to the Raspberry Pi / BeagleBone because of it's strong hardware, x86-ness, and real WiFi support.
