There's a bunch of other pretty cool features, for example:
You know when you start a game and it says "Friends playing this game" and you press the Xbox button only to get your friends list? Well now you can press that button and still get your friends list. Except, this time you can sort people by game they are playing (it's under the filter Activity) with the game that you are playing shown first.
Also under activity, you can tell what map a person is playing, gametype, campaign level, etc without having to go through everyone's gamercard (Before, you would see like Custom Games or just Forge, now you see more details about what's going on). It all shows up in the friend's list.
And if you lag out of parties a lot, they've fixed that with an auto rejoiner. They also added this annoying noise when you join or leave a party. I wish I could kill it.