Here are the things I'm dissapointed in so far.
1. Customizability of the power cards/character sheet. I dislike the way the new character sheet looks in general (extreme dislike). There's a ton of wasted space. Why go from 2 clean pages to 3 pages with a lot of wasted space? And they even removed stuff from the CS!! For example, it no longer shows you the calculations for your defenses and attacks. If the CB math is wrong (as people have indicated that is currently doesn't take into account expertise feats), then many people will have problems figuring this out.
2. The size of the CB in the window. The previous one was full screen. This one is about 3/4 of the screen which makes it feel small and pinched. In most cases, this isn't a huge deal, however when selecting feats it feels like it's just a laundry list of feats with no rhyme or reason to them.
3. Speaking of feats, they no longer give you a short description of the feat next to the name. Now, you have to select a feat and read the full description if you're not familiar with what the feat does. And lets face it, there are a TON of feats these days. Also, see previous comment about the size of the screen with so many feats to browse through.
4. When selcting a MC feat, it then gives you the option to select a skill training. I selected MC Ardent for a character I was building and it only gave me 5 skill choices. I specifically choose ardent because I wanted the MC feat and the diplomacy skill granted by the ardent class. Only, it wasn't an option. I was able to type in "diplomacy" and it popped up for me, but I think this is a huge issue for newer players if they are not familiar with the class skills of each class. I knew what I was looking for in this instance, but many players could miss out on skill training if all the choices don't show up.
5. We are not unable to use the mouse wheel to scroll through selction menus. This is a huge pain. See previous comments regarding feats. There is a huge selection of feats to choose from and not being able to use the scroll wheel on the mouse makes it tedious to scroll through them all.
6. Inherent bonuses are missing. My group has postponed our new DS campaign until the CB came out with intent of using DS builds and races along with inherent bonuses. This is a big dissapointment when they take away functionality from the previous version.
I'll update this if I think of anything else. I realize some of this is aesthetics and I'll just need to get used to it. But why remove functionality for this when it was clearly useful in the original verison. WotC should have launched a Beta version for a month while we got acclimated to it.