I got to see "This is the End" tonight. I'll leave my thoughts below.
First, I must say I went in purposely blind into this film. I had scene only the trailer for the original "Jay and Seth vs the Apocalypse" short from a few years ago. Beyond that, I never watched any of the trailers or tv spots for this film. For a while I just never got around to seeking it out and then close to the release I just decided to take on the movie cold. I had read one small review that described nothing about the film except a clarification that it was more horror based than the early trailers let on.
All that said, I pretty well loved the film. I thought much of the humor played well and I think the film should please most audiences.
A few things will certainly help your enjoyment of the film.
As you probably know, this film features actors playing fictional versions of themselves. Nearly all of the actors in this film have been considered part of the "Apatow Crew" for many years. Most of them appeared in either Freaks and Geeks or the later series Undeclared, and in the steady stream of comedies that came out in the middle of the last decade. As a long time fan of the shows from these actors' early years and of many of the movies they later made together, I feel I was fully primed to enjoy this movie and to be entertained by these particular actors, who have been friends in real life and on screen for more than 10 years bouncing off one another. If you aren't a fan of these actors or at least some of the projects they've done over the years, then your mileage may vary.
This film plays like a cross between Wes Craven's New Nightmare and Tropic Thunder. Imagine if instead of spoofing hollywood through fictional characters if the cast of Tropic Thunder played versions of themselves, but then in a horror setting.
The public personas of these actors and their involvement in a steady stream of movies and shows provides a sort of backstory for the characters. In some cases the characters play into the public perception of the real actors, others purposely invert those expectations.
While the actors are playing versions of themselves, they do remember to allow their roles be characters. The various inter-relationships of who knows who, and various grudges and things while fictional, all do feel probable at the films outset.
All of this provides fuel for what really drives the film, which is character driven conflict. Since much of the film involves the cast attempting to ride out the apocalypse at James Franco's house, the actual plot and conflicts of the film is almost wholly dependent upon the interactions between the characters as they attempt to come together to figure out what is happening and figure out how to survive. Highly stressed and highly intoxicated, their struggles through the apocalypse are ripe with humor.
I was really impressed by how much focus there actually is on the characters in this film rather than a dependence on the actual action or really even the details of the end of the world.
But oh man is this apocalypse glorious. I'll spare the details but I must say, I was pleased with how horror based this film turned out to be beyond just the "possessed Johnah" scenes that have shown up in some of the trailers. The film effectively riffs on both modern and classic horror tropes. The nice thing though is that it never outright feels like it is a horror spoof or anything but rather just a presentation of how these particular people would act in a given situation.
This film is like a bizarre combination of Tropic Thunder, Pineapple Express and Shawn of the Dead. Again, I may have just been primed due to my fandom of many people involved in the film but really I thought the film was very well put together, well acted and ultimately really well written. Some may feel that it meanders a bit in the middle, which features some obvious improv and most resembles scenes from East Bound and Down but these scenes are entertaining enough. I wasn't really looking forward to this film, it was really a matter that I would see when I would see it, but now I can definitely recommend to others to see it as soon as possible and with the best crowd you can.
9/10.