The Umbrella Academy takes a very interesting concept of children with super powers adopted by a billionaire to form a superhero team, but squanders its potential. The story doesn't focus on those origins though. It uses that as the history that led to this fractured family. We are filled in as we go with flashbacks of their childhood. The plot is messy and lacks focus, and the organization they're at odds with leaves some extra holes.
The characters are mostly shallow, and lack real development. Diego can be summed up as "angry at daddy and the world". The rest aren't much better. Five's crazy history takes you for a ride only to leave you with more questions than before. And Vanja's story makes less and less sense as mysteries are revealed, leaving you asking, "Just why?"
The main issue I had above all, was the ridiculous action scenes that undercut the serious tone. The bowling alley had me cringing hard. They try to present these perilous situations and dilemmas, but their silly approach undermines that as does the unrealistic bullet dodging and ridiculous action. Sure is nice when the bad guys wait and let you act before just gunning you down. It's mostly false-peril for the characters, and when something does happen, it seems contrived and forced rather than a natural consequence of the story's development.