First we gotta get high.
Threequels are always the letdowns of trilogies. They either get too epic, or are comprised of four scenes, being the introduction, the pointer scene, the war, and the finale. So yeah, that's still epic I suppose, but fortunately this film didn't follow that formula. Rather this trilogy can be seen as the majestic original, the overly serious sequel, and now the friendly comedy.
Once again, director Barry Sonnenfeld returns to the franchise which one could continually sequelize after the original because it'd be impossible to recapture the original's mythology in a sequel, for once you see it for the first time, the mythos behind it is somewhat spoiled, but in a good way the first time. The rest are just opportunities to play around with it for better or worse. I think that's why so many people hated this movie. They seem to expect it to carry the same mythos as the original, when obviously it can't. Even Josh Brolin received great praise across the board as a young agent K, and I'd agree with them. It's actually a quite comical performance given that Brolin has done so many serious roles, because now he's doing the same, but making it funny. That's called range (take the hint Mr. Clooney). Hence, the franchise can still offer something new-ish and funny. And if you can accept the fact that you can't recapture the original's mysticism, then you shouldn't have a huge problem with this one since the story is much less convoluted than the last one.
Now a decade later, J (Will Smith) is forced to travel back in time to 1969 to once again fix a problem which K (Tommy Lee Jones) is responsible for creating, except this time unknowingly. So right off the bat it seems like a repeat in the plot outline from the last one, save for the time travel gimmick, but because the story focuses so much on J & K rather than the plot, it works a lot better than the last one. Granted it's disappointing that Jones doesn't get as much screen time in this film, but then again, they've already done that on screen duo twice, so it's interesting to play around with a slight twist on the partnership, a la younger K. This also provides more humor as we see how they try and tolerate each other's company in the same age range, though in K's generation. And we get some character development in there as we learn why K is so socially detached from the rest of the MIB. So basically by keeping its distance from its own zany plot, this film takes us back to the crazy 'on the job incidents' which made the first one so funny. Granted it's not as funny, nor in the same way since it's not completely new, but you get the idea. This is more about J & K's journey together than the plot, and that's why this works so much better than the second film. Notice how I mentioned that twice in the same paragraph already.
What gives this one a big boost is that unlike the plot from the last one, this film's entire plot doesn't take itself too seriously. Actually it isn't really serious at all, but rather just comical. Granted it's serious in the sense that an alien invasion is happening, but it's not done in a serious way. That's why the villain is the most enjoyable yet. Boris the Animal (Jemaine Clement) is like a washed up rockstar who's embraced a bohemian lifestyle and is tripping on too much acid with a badass motorcycle and hippie costume to match. Not to mention he's damn funny. Granted he's not menacing at all like Edgar the roach, which truly was the best 'villain' if you catch my drift, but this guy just let us know that this was a comedy utilizing the MIB universe as a backdrop, and thus works out well. The character development and new-ish approach I mentioned earlier also helps this installment fit in with the second film, except on a much better note.
Overall, neither sequel was necessary, but this one sort of redeems the second film for its convoluted nature. By embracing the fact that this installment is a comedy, it doesn't come off too much as a cheap ripoff of the first two. For the original was introducing us to this world in a majestic fashion, whereas here we're just having fun with it instead of seeing some crappy romcom. And anytime something different can take box office away from a romcom, I'm all for it. For let's face it, with the same three or four romcoms being remade hundreds of times, is a third MIB film which is honest with itself on being a true comedy really all that bad?