The sad news is that the ending to LOST was indeed Deus Ex Machina and was almost as bad as the Battlestar Galactica ending (but saved its crappiness for the final episode cluster rather than stretch it out for a whole season).
Note to LOST storytellers and Hollywood in general:
STOP BEING SUCH FUCKING LAZY WRITERS!
Every single fan idea about the mysteries of the island and the story and every bit of fan fiction about a proposed ending was better than what the high-powered, paid, professional writers of the show came up with. Egads.
The big island climax comes with Desmond descending into the Golden light cave since Jack had been badly stabbed by Smokey/Locke so couldn't be lowered by rope down into it. Desmond goes down but is not converted to smoke. And the golden light was less glowy - in fact, once Desmond got to the cave (which looked like leftovers from one of the Pirates' movies or a Laura Croft set) it looked more greenish-yellow and was much more muted. And then when Jack goes down into the cave - oh wait, our hero can descend by rope into a deep cave with a gaping stab wound! - and puts the drain-plug "cork" back into the hole the light is reddish. Weird how having the cork in let the water flow yet pulling it out dried up the flow (tampon companies are you watching?).
What was most distressing for me was how syrupy and sentimental it all was. I wanted answers and a final spectacular showdown between Smokey/MIB and Jack/whomever (not some cheesy Kirk on the sandstone rocks in Chatsworth and styrofoam boulders) and to find out what the island actually is. I got that queasy feeling I had when I watched the worst part of any Star Trek ever: the scene in Generations where Picard wakes up in the diffusion-filter pinky-out doily parlor with children and a Christmas tree.
First Ron Moore and David Eick give us a great show (2003's reboot of Battlestar Galactica) with so much promise only to basically abandon it to simplistic angels and god did it for their big deus ex machina ending, and now JJ Abrams, Cuse and Lindelof (and the rest of the writing team) decide they're too lazy to bother weaving together their vast and myraid collection of story elements they'd concocted and did their own version of god did it: it was all a dream - Jack's death fever-dream of his life as he ascends that tunnel of light to heaven.
On an entertainment scale I'd give the episode a 5 out 10 and I'd give a 3 out of 10 for living up to its potential.
This is what you gave us, LOST creatives: an unfinished masterpiece. Yes, the adage goes an artist never finishes his work, he merely abandons it, but at least with Michaelangelo we have a vast body of his works and thus the unfinished sculptures are understood on their own merits and technical brilliance. He said he didn't create the figure(s), he liberated them. You LOST guys were working on one series and just walked away from its complexities rather than face them. [Imagine Jersey accent]: Yo, it's lika a body - comin' outta da rocks deh - jus leave it, it's good enuf. You were never liberating a brilliant and complex story, you were just randomly chiseling and then quit.
The LOST-Untangled (with muppets) is now up and is much much better than the live-action slop we got.
ANALYSIS PRIOR TO AIRING OF THE END
[I gave the show's creator/writers way too much credit]
Ouroboros (the snake eating its tail - the endless cycle) ... time repeating. In Battlestar Galactica there was the constant refrain All of this has happened before and all of it will happen again and it looks like that's what we'll get with the finale of LOST. You can't fracture time, it will always re-set.
I see the main conflict as Eloise vs. Desmond. Eloise has carefully manipulated people and events to create a happy timeline - the Alt+B as I've been calling it, where her son Daniel is alive and pursuing music rather than science. Eloise killed her son by shooting him on the island when she was younger than he was and she was pregnant - possibly with Daniel - an ultimate time-paradox. Eloise was trapped after that with the knowledge of what would happen but she manipulated what events she could to destroy the island reality or at least the relevant peoples' knowledge of the place in Alt+B.
Her pendant at left is an open Ouroboros, telegraphing that she believes time is not a closed loop, so believes she can fracture it and proudly wears this sentiment as jewelry.She knows there are now two timelines and wears that knowledge as well.
Eloise can't control the discoveries nor the impact of her son's time experments in the timeline in which Desmond goes to see him at Oxford and I suspect that it is Faraday's time experiments which set this all in motion in the first place, he is the Ouroboros - time loops again and again because of him. Eloise helped explode the bomb to undo her murder of her son, which allowed her to see the alternate timelines.
Eloise's husband, Charles Widmore, in the island reality has blasted Desmond with electromagnetism but never really explained why. I suspect that Widmore had reason to believe that Desmond would be able to see both (or all) timelines through this exposure since the island had displayed unusual magnetic properties and other phenomena. So island Widmore activated Desmond's quest in the Alt+B timeline that is fracturing all of Eloise's hard work. There should be a showdown between Desmond and Eloise. If the show it true to form I expect some rich irony in the outcome. Desmond may think he's doing all of our characters a favor in Alt+B but he is probably provoking time (and the island) to re-set.
There seems to be a balanced scale effect happening - most evidenced through Ben: as he grows more sweet and principled in Alt+B he becomes more evil on the island. Desmond is active in Alt+B but passive on the island.
The concert in Alt+B seems to be where it is all set to manifest (kinda cheesy). Desmond is assembling the principals there while Smokey/Locke is still trying to assemble who he has left on the island. Smokey want them to die - but they must kill each other (even if by accident) and now he has his instrument - Ben will do it.
The ending could have gone many different ways but the show's creators and writers had to narrow it down somehow and I'm okay with a Desmond-Eloise face-off. She is the Controller, so carefully trying to shape one reality to give her and the others happiness (the price is their ignorance), and most importantly have her son's life back. Desmond is the destroyer - but perhaps unwittingly. It would be most helpful to find out Widmore's motivation for putting Desmond in the magnetic field and see a shot of Desmond's POV in that magentic field, and if we don't get that information the writer's have been lazy or sloppy.
I see the island as a living thing - although not sentient - that exists outside of space and time. It can't be found unless it or its agents find you. It is a time-space well, drawing to it those people also outside of spacetime. Again, a paradox: people the island seeks have to have been to the island to acquire such properties. I'm sure hoping Abrams, Lindelof, et al are not going the Battlestar Galactica route and we end up with another deus ex machina god explanation ... I'm worried because of Allison Janney/Earth Mother Hippy's comment about the golden light in the cave, "a little exist inside all men."
Now, Smokey/MIB/Locke has one motivation - to destroy the island - MIB shattering the wine bottle after Jacob gave it to him is his way of telegraphing that he will not even try to remove the cork to get free (remember, Jacob told Ricardo/Richard that the island is the cork holding the evil on the island?) ... no, MIB/Smokey will break the bottle - attempt to destroy the island itself ... the only way this seems possible is for him to let the light out of the cave