I did not think this film series actually needed another film to conclude it. And I still don't even after watching this film. Warning spoilers.
Okay, short summary time. Night at the Museum's plot is basically the magic that brings the exhibits to life is ending and Ben Stillers character must go and find a way to restore it. Unfortunately, this means travelling to UK to go and find the only people/exhibits who know the secret of the tablet/tomb. Wacky hijinks ensue and basically Ben Stillers character ends up alone and probably depressed.
This is mostly due to the fact that at the end of the film, they decide to leave the magical tablet in the London Museum so that the egyptian pharaoh can be reunited with his parents every night. Unfortunately, this means the normal exhibits on the US side can no longer come back to life every night. I mean, ignoring the bureaucratic nightmare that involves giving two precious exhibits like a gold tablet and the mummy of an egyptian Pharaoh to a foreign museum, this ending is a bit of a downer in a lot of ways. Sure, they do get revived again 3 years later on when the exhibits are loaned to the Museum of Natural History but that's not permanent. It's a bit of a kick in the pants for anyone who really liked the characters from the first two films.
And that's not even going into what Larry; the main character, must be feeling. I mean, the dude has NO friends at all other than the exhibits it seems. You never see him interacting much with anyone but the exhibits. He lives by himself. His son probably went to Spain and doesn't see him often. He doesn't seem to get along with his ex-wife considering she's never seen. So at the end, when the US museum loses the tablet, his friends are basically all gone and he ends up taking the rap for the SNAFU at the beginning of the film and ends up being fired. I mean, that's a pretty horrible turn of events. So like I said, a bit of a kick in the pants for anyone who watched the previous 2.
But how is the film other than that? Well...it's neither great nor horrible. I would rate it mediocre or average really. The problem is that the film seems to muddle along a fair bit and it's like the film doesn't quite know what it's trying to do. I feel like they had an idea for a film but they didn't flesh it out enough and basically inserted a fair amount of random scenes to try and buff the film up to a viewable length.
If you're a fan you can consider watching this probably because it's going to be the LAST film in the series because the whole storyline seems pretty conclusive to me, what with Larry having said goodbye to the important characters in the film. If not, you can probably consider giving this a pass and wait for it to come out on TV or is on sale for 5.99 on bluray.