Ok lets begin with this:
Although the reveal, as an episode had flaws I do like that Xander Berkeley is Red John. Despite what people say he is one of two on the list that match the description given by Rosalind Harker (given that time has elapsed and that's why he has less hair).
The flaws in the episode itself that a lot of people are complaining about however are easily explainable, the two most common being that 1) Patrick bought in a pigeon and 2) Red John called the police. I think the pidgeon, like the gun, was already in the church, placed by Patrick earlier under the seat, which is why he sits down but doesn't take the gun until he stands again, he was actually getting the pigeon! This is why the bird wasn't found when he was being searched. On this same note, people are also complaining that Red John lost BECAUSE of a pigeon. I say 'why not?' Red John is a murderer/rapist he is obviously very psychologically damaged, why shouldn't he have an irrational fear of pigeons? Although a bit anti-climatic, I don't have a problem with it.
On the subject of Red John begging for his life, running and apologising (the blinking was stupid, I'll give you that) I thought this was GREAT. Red John is a coward! His M.O. and general evasivenss is proof of this. This is what a murderer looks like, not some larger than life para-mentalist who has ten alternate plans which come forth in one 40 minute episode so that he and Patrick have an all out contact/intellectuall war, with an eventual life shattering reveal (which some people seem to have expected).
OK, that said:
Strawberries and Cream's "Red John" reveal (Timothy Carter) was, in my humble opinion SO much better. Had they ended with something anywhere near akin to this I don't think we'd have any real complaints, from anyone.
Finally and most importantly is that things were not and apprently are not, going to be explained. This is where I'm frustrated beyond belief, these are the details we have waited years for, the who, how and most importantly why? The answers to our questions! All the events that have occured around Red John and the CBI, apparently now, they're just not that important and that is the truly upsetting part of this whole business.

I suppose the question now is 'where to next?' with Red John gone I honestly don't see what will make The Mentalist survive. I'm going to continue watching it of course, but I hope it doesn't just revert to another crime drama, the Red John aspect was the dak element that pushed everything along and were the episodes I held out for, I hope they can create something just as good to keep the audience wanting more, and honestly I hope they respect the fans enough to actually give us some answers.

P.S.
If this reveal turns out to be fake again i'm not exactly going to be happy, but i'm not going to be unhappy either.