I think the biggest flaws of TLJ came from what little Abrams gave Johnson to work with. I honestly think the whole Luke plot-line, which seems to be what most SW fans who didn’t like the film complain about, was as good as it really could have been considering where Abrams ended TFA.

If Johnson gets to do a truly original SW trilogy I think it could potentially be really interesting. I think TLJ was simply too shackled by TFA’s re-use of OT ideas & iconography, especially Abram’s “Mystery-box” ending. I also don’t think Johnson works too well with “kid-friendly” material. I think if he was allowed to go in a direction more similar to Rogue One it would work a lot better. The darker aspects/moments of TLJ are IMO what worked best.