So far I like it. Haven't really used Halo, doesn't seem that cool. Also using it is really weird. Here are my initial observations:
The PA pie controls are much better than the CM ones.
Changing colors of the navigation buttons are cool. But overall layout is determined by the AOKP section, which isn't as good as CM's version of changing nav buttons.
Per app ppi is useless to me. And going into the settings and changing it to "Stock UI" where it says "none of your apps will be changed" is stupid and doesn't fully work. It still changes 14 apps that I have to change back to the default settings individually.
The AOKP recents app is much better than CM.
Lock screen controls have been included for both AOKP and CM, so they fight with each other. That should have been thought out a little better.
The CM messaging popup looks different now. Has a white box in the middle instead of being a constant dark-gray color.
Overall I have not come across any major differences pertaining to my usage. Some minor improvements over things I used are nice. And minor improvements is what I was looking for. But this also gives me a ton of options if I decide to switch it up later on down the road. And now I won't have to switch between any of the 3 major ROMs.