TV series:

• the casting – sometimes they get it exactly right
• it was funny (like the book) but the sadness – and therefore the message – was far more prominent
• beautifully done shifts between the past and present

Book: Fleishman is in Trouble by Taffy Brodesser-Akner (although it was in my favourites in the year I read it, I never reviewed it).
TV Series: Fleishman is in Trouble (streaming on Disney in Australia).