"Amused, amazed, and moved" always by MIB 1997, 2002, and now 2012. Effects of aliens, humanity of humans - "I just can't get enough". Great homage in Doctor Who spin-off grown-older companion Sarah Jane (actor Elisabeth Sladen d.2011) S4-3 Vault of Secrets.
Starts with high heels, tight black leather dress low cut short, tall boots. Lily (Nicole Sherzinger) pen-pal brings birthday cake to one-armed Boris the Animal (New Zealand's Jemaine Clement) "just Boris", gruesome alien with British accent whose hand and body projects deadly darts and keeps nasty hand-size smart scorpionish beastie inside, where else?, his hand. All body parts open like maws of claws. Of course he escapes from lunar prison to "rewrite history". His "small step" is a soaring leap.
Cut to New York, where Agent K (Tommy Lee Jones) introduces Agent J (Will Smith) to neuralyze crowd into forgetting. J still invents unusual yet practical tidbits for his neuralyzed victims to remember, ex. tell kids the truth. New chief O (Emma Thompson - she is brilliant comedian) gives eulogy for Zed in squealy language. The whole bit shows K flat, cold, serious, monotone, no twinge of expression, intensely fierce only when interrogating, almost a smile when he mentions his Last Meal. No sense of humor for the 14 years of their partnership, "surly".
After wrassling giant 12' carp, squirting mustard up its nostrils for one piscine sneeze, J has to save young K (Josh Brolin - this better than Gangster Squad), convince him to kill Boris rather than imprison him 40 years ago, and put the protective Arc-Net around Earth on 16 July 1969, to exterminate the cannibal Boglodite race before they can destroy Earth. Space guns, explosions, chases, aliens, handsome hunks. Even young O (Alice Eve) hints at romance with K. Cool high-tech monocycle rotate giant wheel around driver. What could be better?