Krupski:
majenko:
... and you're barely scratching the surface ...You forgot to mention the 160 mil spacing of the digital headers - makes it almost impossible to use perfboard / stripboard for prototyping.
And why cripple it with an Atmel chip anyway? That was a bad idea from the outset
Another nice option would have been a jumper to select the chip's Vcc - set it to 3.3v if you want to use 3.3v peripherals - saves all that faffing around with level shifters or butchering you board to make it 3.3v.
And why the hell did they use a full size USB socket? Those things are useless - On one of my UNO boards I have to hold the cable in the right position to be able to program it, and the sockets get in the way of any through-hole components on the shield above. I have little foam pads stuck to my sockets. Mini B sockets (like everyone else in the industry uses) would have been just a bit better
Gee... I have to agree with everything you said. I forgot about that goofy pin spacing problem. I wonder if it was a mistake in the initial design that had to be carried through for "compatibility" or if it's intentional so that specially spaced "shields" (i.e. something they can sell) have to be used instead of plain old perfboard?
My guess is the latter 
But that's the cynic in me getting out again. Wait a minute, I am the cynic in me!!!!