I think that a certain majority on board the Lostpedia freighter have been suffering from Endoflost Cabin Fever - a very specific form of the condition. Symptoms include dissatisfaction of answers, general negativity, and nausea.
On a serious note, however, amongst some of us at least (myself inclusive) there has been a sense of impending doom - that being the end of Lost, and the finality of some of the answers that we are getting. One thing to remember is the fact that we have been given answers before, and more often the not, the truth has been skewed by either a character's perspective or motive; and I think that this is what has happened again. I am referring to Flocke's 'admission' to impersonating Christian. Firstly, having watched that scene again, Flocke's answer seems to have been delivered in such a way that it was a spontaneous lie; something which the MiB has done before in order to manipulate people e.g. Richard in Ab Aeterno. In this case, his intention was to 'recruit' Jack, and his method was to provide him with an explanation for his father's post-death appearances, and to link himself with the explanation via good intentions.
This obviously leaves Christian's appearances unanswered. However, I am of the belief that he is a 'ghost', just like the ones that appear to Hurley. Going back to 'Everybody Loves Hugo', and the explanation of the whispers - an explanation which I was perfectly satisfied with, although perhaps the delivery was a little rushed - this was a sort of confirmation of this 'ghost' world, and that Hurley was in fact never crazy for seeing them, he was just special. Then, why did Christian appear to Jack? I've always, and I think that many of us have, thought of Christian as being a little different from all the other appearances and manifestations. Well, I think that Christian is the equivalent of Richard in the land of the dead; he is like Jacob's assistant, telling people when they can go and when their work is done etc. And I think that with this 'job', he was given the ability to appear to whomever he needed to.
Finally, looping back to the Cabin Fever thing, I reckon - because Lost is coming to a close - we're assuming anything that addresses a long-standing mystery is the final explanation and a moment for the writers to tick one off the list; but I just think that we haven't yet been given the right heading. And, ultimately, I think that Jacob will be this heading, and that these mysteries will properly be tied together through his character. If we have a Jacob-centric episode, I think we will be given a lot of answers, and they will be able to be considered the truth.
Of course, if I am wrong, then the Christian explanation will be very frustrating indeed; but I am reserving judgment until the end, and I think that we all should. Lest we end up jumping overboard.