To say this is a rival is a bit overstated. It costs $299 versus the Pi's $35. Sure, it has more features (1GB RAM, QC CPU, etc.) but the price tag immediately puts it in another class.
But to be fair to Microsoft, the purpose of this board isn't really anything like the purpose of the Pi, so comparing the two is really just flawed to begin with. It should really be compared to boards like tge Arndale ( http://www.arndaleboard.org/ ) and in that context the price is actually quite reasonable even if you value the the Windows image license at $0.