In many ways Armageddon is a classic Ricky Gervais special; huge laughs, beautiful construction, well-articulated points and all that great jazz that has become his signature ...
BUT ...
.... There is nothing new!
The subject-matter has been exhausted at this point, yet he is still trampling that same old ground and making the same old points.
There are also references to bits by other comedians, as there have been in his last three specials. This is by no means an accusation of stealing material or any such nonsense, however, it should be noted that less popular comedians have received a lot of flack for a lot less.
My last criticism would be that a lot of his material seems be aimed at twitter. Twitter and the real world are very different places, so when he talks about 'people', it comes across as almost hollow because his characters are based in that world.
This might sound like a bad review, but it isn't. Armageddon hits the same high standards we're used to seeing from Ricky Gervais. Unfortunately, 'same' might be the most important word in that sentence.