To me, the movie greatly depends on whether you've watched the previous movies. If you have, your standards would be rather high and you will walk out of the cinema rather disappointed. If you have not, I suggest watching it as it is a great movie alone.
The movie's plot is rather basic with a bland twist and a fight scene. The build up is good but followed by said bland twist. What compensates for the plot is the dynamic duo, Chris Hemsworth and Tessa Thompson, who I wish to see more as a pair in the future.
If you have not watched the previous three movies before, you will have not known about the aliens and the explosions MIB is famous for, therefore you will be fascinated. However if you have watched it before, the explosions and monsters are recycled and there really is nothing new, thus dull and dry.
Therefore, I suggest walking into the cinemas with a fresh new standard and do not expect the same from the previous 3 movies.
-Isaac, from Clout Grandpa