Well, I managed to get tickets to a sneak preview of MIB3. And I'm going to have to say that it was quite disappointing.
I won't go into too many details because the movie hasn't been released yet but I will say that after 10 years, it seems like the writers have pretty much lost the feel for the MIB franchise. The actors go through the rote, as does the script; big alien invasion etc, J being snarky, K being expressionless, but it never really grabs you. Instead it feels like they're just going through the motions without any soul. Plus it didn't help that none of the characters were memorable in the least, or interesting.
Plus I'm totally disappointed at the scarcity of Tommy Lee Jones in this film. WTH Columbia pictures.
IMO, MIB 1 was the best. MIB2 was decent though it did go through the same motions/plot that MIB1 did, but it at least managed to add something new to the flavor. MIB3 however? It's MIB2 but turned stale after 10 years.