IMO Rian Johnson's best move is Looper, which is specifically good because it's a very literal subversion of the sci-fi time travel genre niche. But in truth, he really hasn't made that many films.
And other than the aforementioned Looper, I haven't really seen the films he's made. (Brick, The Brothers Bloom, and Knives Out). Though his Breaking Bad stuff is p good.
The decision to make him director in the first place, regardless of my opinion of him, is kind of weird considering his lack of experience (especially with the kind of sci-fi [or science fantasy if you prefer] that is Star Wars). I don't actually disagree with him wanting to do something different with the universe--the body of work that is the films themselves before the new trilogy is pretty cut and dry. HOWEVER. The execution is laughably bad, and while Disney made a decision to axe most of the EU, the fact there are extant blueprints of Star Wars stories done RIGHT and that are different from the Lucas' approach out there in the world that WEREN'T TAKEN ADVANTAGE OF is just bad research/design/whatever. People have written books/designed games/animated cartoons about Star Wars that do something different and are a legitimate part of the "Star Wars Fan Canon"tm.
To be fair to Rian Johnson, it just seems like from a creative perspective, the elements of Star Wars are things you either GET or DON'T, and many people just DON'T. EDIT: Hell, even Ron Howard doesn't--and he's Lucas' long time friend and sounding board.