While Battlefield 3 has improved quite a bit since its somewhat sorry state at launch, one critical flaw has remained: an awful weapon customization UI. The game has approximately ten bajillion weapon loadouts, but you never use most of them because it's just too much of a pain to navigate through the tedious and inefficient UI. And while PC players will often lay blame on consoles, I've spoken to the peasants and some say the same thing.
Anyway, the situation is finally improved today, though probably not in the way you expect. That is to say, there's a new and improved weapon customization UI, but it's via Battlelog. While in-game would be better, this is a hell of a lot better than nothing, and it's nice either way to be able to swap accessories in and out of game. Besides weapons and scopes and such, you can also choose between camos, specs, and gadgets, and also various vehicle specs. Note you can access dropdown menus by clicking an individual item -- very efficient.
Reddit user "prostynick" praised the feature, and commented next he'd like to see specific setups you can save (e.g. aggressive recon and passive recon), to which DICE replied, "Yes, we're hoping to add more features; this is just the first iteration."
Hit the source and click the new Loadout icon at the top to try it out for yourself.