My guild is still a bit behind because of a few last-minute issues with our roster (some members quit WoW in the last month, been a mess to replace them).
This first part of the first tier looks very challenging.
Some combination of Stone Guard dogs can be really hard to manage, second boss requires you to use the tricks of the crystals to make it viable, third is a time-race, fourth is very easy, Elegon feels hard and we haven't tried the last one yet.
On paper some heroics look really hard.
Despite all of that I'd say that T11 was harder, imho. Not much, but a bit harder for sure. Altough it's hard to make a 1:1 comparison since they still have to release more raids of this same tier, whereas T11 was released all at once.
So far I'm pretty satisfied by the fights, altough I still hate mechanics like StoneGuard/Halfus, where a boss changes radically from reset to reset.