Unusable arrow and edit key layout (that can't be reprogrammed).
It's not that hard, and you move your hand less far than you do for dedicated arrow keys.
Fn key placement that overloads your right pinkie even more than a normal board. Slippery grip tabs that allow the board to move around when typed on.
To each his/her own I guess. Isn't any 60% board going to require a lot of use of some kind of FN layer though? I'd be interested to hear the counterpoint on this, actually. I'm not having too much trouble adjusting so far, and I'm only a couple weeks into using this thing regularly.
No aftermarket keycap choices.
I wouldn't mind a few color options for modifiers, but yeah, this isn't the board for you if you're into blowing a fortune on changing your keys on a whim. The idea is it comes with nice, functional keycaps out of the box and you use those. Definitely not a great keyboard for a hobbyist -- more for, you know, just typing on it.
ABS spacebar.
I'm always surprised people care so much about this. When it starts to (gasp) show signs of wear, you could always buy a replacement using some of the $ you've not been blowing on replacing the keys every time a new group buy comes up or whatever

Only one useful mod - can't change the switch feeling except by buying ANOTHER overpriced board and swapping domes.
Again, not a keyboard for hobbyists. I personally love the way the switches feel and would rather just type than spend my time ****ing around with switches.