Nothing that alters-improves the game so far, "European" line is a pity (not because extra planes) but because it means will never have a French tree, and also since they are all premiums without a research-able tree so it is not a "line", just a few more premiums.
I cannot understand why this is called 2.1. I really was expecting the "hardcore" mode without silly caps and magical appearing - disappearing ADA's to see if there is any future hope in the game, but Nope, not yet.