The first "Men In Black" movie was novel and inventive and very funny. The second was, well, horrible. The third is a mess, but Josh Brolin's performance and a reasonably funny script made it worth watching. This one is just ... innocuous.
Tessa Thompson is a young girl whose parents are neuralysed (MIB-speak for a short memory wipe) - she sees it happen, and grows up wanting to be a MIB. She of course succeeds, and is partnered with the handsome - but also crazy and irresponsible - "H" (Chris Hemsworth). Inevitably, they're handed a task that turns out to be a lot more problematic than it appears to be. The action happens in New York, London, Marrakesh, and a couple other places. Thompson (Tessa ... Emma is also in this) and Hemsworth are an amiable and mildly funny team. As with previous installments, their character arcs are devoid of logic in the service of not-terribly-funny gags. Thompson (Emma, this time) brings the best delivery (and acting) and they really should have given her more screen time.
A lot of people have been calling this the end of the line for MIB - I hope they're right. Because if they make another, it can only be worse, and this one at least isn't terrible.