All, I enjoyed the first movie and my daughter's loved it. I own the Meg DVD but can't say I'll buy Meg 2.
The movie was ok but not even close to believable. This reminded me of an upper level B movie. The giant octopus scenes were junk, the plot was suspect. The replacement cast was off point My daughters said it was good but I didn't hear screams to see it again.
Over all it's a 3.3 and unless they come up with a sequel that is just impressive, Meg 2 should be it. There was a hint of trainable megs but please do no do it!