My big issue is the lack of custom items.
I DM a pretty stock game of 4e, but when it comes to the 4e magic items...they are missing much of what makes a DnD game great to me.
My loving wife...and co-dm...bought me the encyclopedia magica set for my B-Day. Now, THAT is how you do magic items.
As I'm slowly converting items over, I'm really bummed to see the CB not support custom item cards.
Even the old CB had weak support. Just try to add a helmet that grants a +1 AC bonus.