In case you haven't been automatically notified, there is a 5th DLC for Borderlands2 that became available recently.

Titled Commander Lilith and the fight for Sanctuary, I've played it through once and have to say it is well done. Elite loot chests aren't very prevalent, but the loot drops from NPCs and mission rewards made up for it as far as I could tell.

It was fun, and it was free since I already had the required main game.

I see it was just released last week. Free to all until July 8. Thanks for mentioning it!