Before the superhero genre was honed to a fine point by Batman Begins & The Dark Knight and then weaponized into unstoppable entertainment by Marvel Studios, it wasn't such a winner. M. Night Shyamalan saw that comic books had massive mythic appeal which could be made into great stories. So he invented his very own super villains & heroes in a very real world we could recognize. 

I thought that Unbreakable was a one and done sort of experience. There was no open ending for a sequel. Sixteen years later came Split. This psychological horror movie seemed to be another stand alone until David Dunn appeared at the very end of it. 

Trilogies much like racing trifectas are hard. You can go too big or small or maybe not at all which I think was the case with Glass. When some character meet for the first time, it can catch fire or feel stilted and subsequently boring. I wanted to love this movie, but no amount of cannabis or hype can cure a plot where great characters are not given enough to do. Glass half empty or empty container where I store my weed makes me disappointed and a little let down. Might be time get nicely blazed and go watch Superman II again.