Decent watch, probably won't watch again, and can only recommend if you REALLY liked the first on and MIB International isn't available.
They literally start the movie by subtly explaining why the formula doesn't work without Tommy Lee Jones and Will Smith, hell Patrick Warburton would have been an AWESOME option to be in the movie for real.
This is a weird one because the movie is well cast, it has an interesting premise and villain, and the story is well written up to a point. And hell adding Rosario Dawson makes anything better, but this one just lands weak. They seem to do a worst job of showing us all the same tricks (sometimes literally) from the first movie, but Agent K feels shoehorned in, and the resolution isn't satisfying at all. Maybe if there was an epilogue, but the movie is from the perspective of the MIB and they're planet side only.
The threat is also weird. They could have taken their time and did a mystery movie, but instead they put a clock on it and rush it so it's barely interesting and there is no connecting logical dots for deductions. Then it's arbitrary when the do figure it out, and there is no explanation of why, how or what actually lead up to that. It is literally no information leading up to a fact, then no information resulting from that fact other than a simple reaction.
The first movie is just better, and MIB International is a lot more fun.