It's a mess of a ton of healers, healing low damage on random people randomly stepping into fire, without anyone knowing what anyone is healing and how he is doing it. The result is that you have little room to feel you are doing anything important, barring the exception of an overgeared healer carrying just dinged healers but that's a nonstarter since there's no reason being in the raid.
The thing is, you can't say "raid finder is like that for all roles" because tanks can have a limited sense of self worth and a feel they control the action in a sense just as they always do, and the dpses, can often properly can go on a dps race. Healing in raid finder feels like there is no race, just a mess that it will be 90% of the time an overheal-fest and 10% of the time 0 good healers or 1 overgeared one doing all the work, that he shouldn't be in there anyway with that gear.
I get sense this mess, this absolute mess in 25man raiding that lacks proper coordination, is one of the reasons that the only serious raiding tier is going strictly 20man only. "Those extra 5" always seemed useless. 10man is small and 15 seems fine so something between 15-20 seems optimal and even raid finder may benefit from something like that.