There wasn't really any sort of a build up to your "mighty" sacrifice. It's like...You deal with Autumn, and suddenly "Oh by the way, you'll kill yourself activating Project Purity. Someone sabotaged it!"...Wtf? I know that type of ending sounds clever to some people, and it certainly is emotional, but it's robbed me of any desire to play through the game again any time soon...I've just gone back to Fable 2, lol. There wasn't a build up, and it felt more like someone had literally thrown it in at the last minute because it would be really unexpected, which I know probably isn't what happened. Unexpected ending doesn't always mean a good ending...And the sabotage bit didn't make any sense. If the Enclave sabotaged it, they aren't all that bright. If your father sabotaged it, I guess he's insane and decided he wanted to see you in the after life sooner rather than later? It didn't feel "Omg that awesome and shocking!" It felt more like "Are these people that stupid?"
You want to know the worst part? I had Fawkes with me. He would have survived the radiation, why didn't we send him in? WTF! Did they really expect me to not bring Fawkes along? XP
And the epilogue...Man, that wasn't really a Fallout epilogue. It was just a minute of congratulating me on discovering the true meaning of sacrifice. And possibly Christmas. I get it, I'm playing a messianic figure. Waters of life and all that, yay.
But what happened to my allies? my enemies? The Brotherhood? Megaton? Tenpenny Towers? Et cetera? I realize we might find some mention in Fallout 4, but it was really dissapointing after the epilogues of the first two Fallouts.
Also, and I really, really hate to say this since I'm not usually like this as you've all seen with Fable 2, but Bethesda, seriously.......200 slight variations on a short speech (depending on your combination of good and evil and choices)and background photos isn't exactly the same as 200 endings.