H Sha is actually very easy, the dps requirement is a bit high on platforms, but thats really more about eating balls and making sure you have a good backup non tank soaker incase a platform is slow (Fury warriors, Rogues, Iceblock and BoP's make this trivial). Phase 2 Sha is kind of a joke, it revolves around 3 people playing catch and healers learning how to handle Huddle.
The hardest part of the fight is like people said, just getting enough practice on it, because it is very long; and the whole Lei Hope buff mechanic is just silly.
Edit: Every guild has their most difficult encounter. For us; H Ambershaper was just a nightmare getting constructs down properly. Vizier ofcourse was a rediculous fight pre-nerf and still suffers really annoying RNG as to where the duplicate might spawn. And don't even get me started on pre-nerf Reset Kings!