What would make it good?
Especially for those that hated TFA what would TLJ need to do to be good for you?
For me it would need to give a good explanation for Rey, having her mind wiped or something of the like, being so powerful. And make sure they make her a more modest character, sort of put her in her place. She was just too powerful and inexplicably so in TFA so something needs to be done with that. Best case scenario is she turns to the dark side and Kylo to the light and everyone teams up to fight this super powered anti-jedi.
Must be vastly different from ESB. TFA was just too much of a rehash and TJL needs to distinguish itself. The trailers are already suggesting this is not going to be the case but hopefully it is misdirection.
The nature of the first order and Snoke must be explored and given some credence. In TFA it is just there and does not go into detail or even speculation on how the first order maintained such power after the fall of the Empire. TFA just put it there and demanded we accept it.
Much much less pandering. TFA was too focused on pandering to nostalgia and modern 'diversity' sensibilities and was not concerned with story telling. Disney is becoming more and more notorious for this, seemingly having a 'diversity check in the box list'. I do see how this is not racist or prejudice. 'make sure we have some blacks, Mexicans, Arabs, and Asians in there.' And I swear they better not make good on their threat to start doing openly homosexual relations just for the sake of it.
Do not let the OT characters be belittled and reduced to pathetic again. Han and Leia are pathetic shells of their OT characters in TFA. This better not be the case with Luke, but the trailers are already suggesting he is going to be.
That is all I can think of at the moment, to me it already seems an impossible task.