LFR was quite difficult on the beta, some bosses and trash as exactly said, harder than others. like the last phase of that encounter where the tornados spawn and you have to run from one side to the other (similar to the heroic dungeon fight) the boss is about to enrage and if you have people screwing up, you're dead. (it was overtuned when we did it, impossible to do so it might be much easier, maybe less tornadoes) this was with players doing AMAZING healing and great dps. of course, like I said...overtuned and bugged on beta.
point is, it can be quite a challenge and I have a feeling that if they haven't nerfed and changed the fights since beta, people will whine and complain and since it is LFR it will get made easier.
but as it was on beta, I'm sure people will tell you...pretty fun. *much* different than DS. if it remains unchanged, you guys will enjoy it.