TFA is pretty dry and the author takes some liberties in some of the characterisation, some good, some whatever (Finn is too verbose, and Kylo is a bit different, for instance). And there are some extra scenes.

TLJ is wonderful. Deleted scenes (including Luke and Rey sharing a dance), extra scenes that weren’t even filmed but expand on the characters,. Lively style (there’s an xwing battle sequence where BB-8 is the pov character). Explains many things about the state of the galaxy and connects to new canon as well… The movie really lends itself to the kind of inner monologue and character expansion thing that the novelization format offers, and that’s a part if it as well. It’s great, not in the same way as RotS, but still solid.

TROS is not really much better than the film. The author expands on some stuff, adds some scenes, rearranges some stuff, and it’s obvious that the Story Group participated in the novelization, unlike in the film. So while that makes some of the meh parts somewhat good, it also f–ks and muddles other things and obviously reading a bad part of the story is longer than watching it, so that’s why I say it’s overall not much better (“kiss of gratitude”, Luke constantly telling Leia to go finally die,…). But there are nice things in there.