Just because Apple says the processor is "desktop-class", does not make it so. If it consumes 5W, you are only going to get 5W worth of perfomance. Any half-recent Intel processor will easily blow this out of the water.
About the same amount of RAM then, too. :-)
In that realm, this next generation of 5 - 30w parts from ARM and Intel is performing equivalent to the last generation of core 2 quad processors at 120w. And people did some serious professional work on those kinds of chips.
So, 2013 programs that don't "work" on 2005 hardware? Off the top of my head: SolidWorks 2013, VMWARE running Ubuntu 12 on top of Windows, Avid, Visual Studio 2013.
So basically things 95% of users don't have any need for?