How is the overworld and general difficulty with one tamriel? Has it increased?
Or is it still pretty much the same as before the patch? And what about dungeons (mini,public, normal veteran )?
From my own, short experience, I would say that the "overworld" (incl. Delves) is similar in difficulty to Orsinium, etc. Worldbosse vary in difficulty. The new veteran dungeons are no more difficult the old ones (if you play to the mechanics)-
Overland mobs are mostly the same, with the exception of world bosses, which are a lot harder now, and cannot be soloed.
Well, they actually can, but they are designed to be group bosses.