The difficulty was upped considerably, of course. For example, there is now pends and dune scorps, there is also a Mono-Aether and Ferox Jr., Paradox Jr. and even Osiris Jr. in those new decks, and I doubt any of the old decks are still there.
AI3 isn't to be fail decks, it's supposed to be harder.
From what I've heard, shrieker rush un-upped still beats them very often
Nilsieboy for example made a water rush, and lost 1 game in a total of 300
I played around 50 with DEMA and lost around 3
So no, it's still pretty easy and rushable with upped decks, but with un-upped, it becomes quite hard.