It's kind of a hard comparison to make between the miniseries and this first movie -- I don't disagree that there are things the miniseries did better, but I'm having a hard time separating the miniseries into 2 discrete chunks since it is longer and has the added bonus of completing the story. If the 2nd movie here has flashbacks to the kids, and fills in gaps, then a lot of the things we are looking at now as sort of characteristically incomplete aren't going to last.
The miniseries is less funny, and in a lot of ways tonally more accurate to *my* feelings evoked of the source material. It is darker, and a bit more disturbing overall. It is *not* as well-executed, and in many ways veers away from the source material where this movie feels like a closer complement to it.
It's not a win-win movie. It doesn't have better execution, better tone, and better characters, necessarily. It is a *really* good movie though and distills the first part of the story in a way that is fun, funny, heart-warming where it should be, and manages to be disturbing visually in a way the miniseries just simply couldn't be.
I am very excited to see Part 2, and I would only pray that Muscietti relies more on practical effects, and selects a darker tone overall to complement the story, while bringing back a few "missing" scenes that I was hoping for in the first movie (but can still easily *fit* in the 2nd)