As good as Tim Curry was in that, the 2017 movie has rendered the 1990 miniseries completely obsolete. (Not that the miniseries was ever good).
IMO an important element of the novel was the interleaving of past and present, gradually revealing what happened then in the context of what is happening now, and with it how the children/adults are both the same and different The 1990 miniseries and now the 2017 movie (part 1 with part 2 in the future) separate the two.
Concerning the ending ...how do you do that on the screen?