With the release of Call of Duty: Black Ops 2, the Call of Duty Elite service has now gone free. Activision also updated the Elite app for iPhone and released an iPad version too.
The app has been pretty much redesigned and it looks and works a lot better than the previous iteration. With the app you can of course look at all your main stats such as days played, level, K/D ratio, total kills and score per minute. Unfortunately you won't be able to look at weapon stats, however you can do that on the desktop version.
You can of course customise your classes right in the app too. So when on the move it can be useful if you come up with a new class idea to just push it right away to your game when you next log on.
You can track your challenges to see what you want to complete to gain more XP and level up.
Clans have also come to the app in a big way, it's being called Clan HQ. You can look at your clan, the stats and the members of your clan.
The desktop version is a lot better than the iPad and iPhone version but the apps are a good way to always stay up to date.