I think we can all agree that the trilogy should have been better mapped out up front.
I think we can also all agree that Adam Driver was a standout performer. I thought Daisy Ridley was great, too.
I think we can also all agree that "success" is measured in different ways. Short-term success, box office, is one thing, but Disney has much more than just box office on the line with the franchise. There are ripple effects to each movie. Taken as a standalone film and by the narrow definition of short-term success, Last Jedi is successful. As a standalone film, non-SW fan movie reviewers can appreciate its unpredictability ("bold choices").
But in the context of the saga, its place within the saga, and Disney's expectations for long-term success, Last Jedi is unsuccessful. Last Jedi tried so hard to expand the SW universe that it contradicted it.
Phantom Menace and Attack of the Clones at least felt like SW films, but they were bad, plodding films. A course correction was necessary, and fans of the saga were rewarded with the faster-paced, better-written, and better-acted trilogy conclusion, Revenge of the Sith.
I fully expected the new trilogy to be about the new characters (Rey, Ren, Poe, and Finn). I would have been happy to see their adventures with the OT crew as the supporting players. That didn't really happen.
We got a serviceable New Hope remake that brought back old characters and introduced the new. We got a "one of these things is not like the (8) others" exercise with the movie in the middle that thinks it's a standalone film.
That's where the fast-paced, ret-conning, call-back-laden Rise of Skywalker comes in. Bringing back Palpatine results in getting Ian McDiarmid (and his gravitas) back for an excellent performance. The story is roller coaster ride fun, and the visuals are absolutely incredible. From a Disney perspective, the new film is completely successful. It's the most SW movie since the OT.