The Foundry Dailey mission is online now btw.
I guess this makes it very easy to level with UGC missions alone.
You get XP additionally to kills and level specific loot (I got a rare HD beam rifle yesterday). Apparently the level specific badges don't work properly, so don't pick them as your reward to be on the save side until the issue is resolved.
So it get's a lot more interesting to level a new toon with hundreds of new missions.
Then again, the exploitation of that system has probably already begun.
In addition to missions named "Kill Stuff" we now get "Enter system to resolve mission" so doing 3 missions in the row for the XP and loot is done in as many minutes.
I really hope the rewards are tied to the missions length and complexity somehow.