Sequels are almost always a letdown, and with this franchise, it's incredibly easy to continue sequelizing it with different characters if you so wished. For this sequel however, the filmmakers went with a conventional storyline, and by shutting us out of MIB Headquarters early on, the movie becomes more about the plot and immediate story than the mythology which the first film captured so perfectly.
Things go awry when Agent J (Will Smith) learns that a slimy alien with a killer body (Lara Flynn Boyle) seeks to steal the mysterious Light of Zartha, which if not removed from Earth will destroy the planet. Seems like she's not all that bad, except of course, this time instead of Earth being the target, it would be a peaceful alien planet which agent K (Tommy Lee Jones) saved eons ago, which serves for a nice '50s/'60s era flashback akin to those old television specials, except infinitely cooler. So basically, K & J must go on a detective spree across New York City to find the Light of Zartha which has something to do with a pizzeria waitress (Rosario Dawson).
The chemistry remains almost the same as last time, except J is more experienced, and K is like the rookie trying to remember his old life in the MIB. Funny thing is, K does a much better job at being an agent than the more experienced J. This provides good humor, but again, the story almost immediately thrusts you into the plot, so there's not much on the job incidents. Technically this whole movie is an 'on the job incident,' but because there's more threatening deadlines associated with it from the get go, the runtime is devoted more to plot development than character development, or further exploration into the mythology of the MIB.
Overall, the visual effects and chemistry between J & K suffices, but this needed to backtrack to the imaginative nature of the original than just playing around with a new story. I mean it's still enjoyable, but it could've been more. I did however like the romance played upon because it relates back to the romance of K and his wife from the first film. This too is humorous cause J gave K crap about it last time, whereas K won't give J that satisfaction here. But what perhaps makes it all worth it is the crummy video hosted by Peter Graves akin to those old seventies specials, especially when Spielberg's executive producing credit appears over the crappy tin foil flying saucer dangling from flimsy wires.