Reason being it feels like something's missing. You cannot do an MIB movie without Will Smith...maybe Tommy Lee Jones, but NOT Will.
I loved the storyline and acting, but again that element...missing. Chris Hemsworth as Agent H is amazing. It focuses on Tessa Thompson's Molly aka Agent M who finds MIB after looking all her life for them. She's the perfect agent, but there's NO lag in training because she's been studying this her entire life after her failed career as FBI agent. If they linked her to Will I would've liked it more.
Worth seeing and the special effects are awesome. Look for cameo from Rebecca Ferguson and Kumail Nanijani as Pawny.