My flippant reply back when it came out was:
Essentially I think the character of Luke Skywalker has always been a bit of a weak link in the saga as he’s very bland and virtuous. There’s no real moral arc or big development to his character in the OT.
In the TLJ I think they put forward a very engaging story as to how one man who was once so pure and idealistic almost gave in to terrible temptation, and through the interactions of Luke/Kylo/Rey they demonstrate how the weight of family history can make doing the right thing incredibly hard.
Mark Hamill’s acting is also considerably better than in the OT which helps sell the storyline completely to me. Hoping for some good force ghost stuff this time round.