For my personal opinion, TLJ was by far the worst Star Wars movie, PT included. The writing was lazy and nonsensical. But I won't bother justifying my opinion in detail: I know it's well-considered and anyone who disagrees with me is free to do so.
I saw the movie once when it opened in theaters, and my opinion at the time was basically, 'huh... that was... fine?... I guess?' I didn't hate it, but the pacing problems and logical holes seemed obvious to me from the get-go. And the worst thing was this: I walked out of the theater with no interest whatever about what might be in Episode IX. This was the first time I saw a film in this franchise without giving the littlest damn about what was going to come next.
The thing lingered in my mind, though. I couldn't stop thinking about it and it just seemed dumber and dumber the more I thought it through. I spoke about it with my friends and my opinion plummeted even further. Eventually I watched a few YouTube complaint videos which only served to crystallize ideas I had already had. I saw it once more when it came to Netflix and I could hardly make my self sit through the whole thing. This film is a cinematic turd as far as I can see.
But the OP asked about widespread hate. I will concede that the film did take a lot of money in the total box office figures. However, its ranking dropped pretty rapidly after opening weekend, meaning that people weren't going back to see it again, or maybe that people heard from their opening weekend friends that it was worth skipping, or would be better on video. That drop off is not a good sign. Another clue is in the merchandising; TLJ toys and other merch warmed the shelves. Stores couldn't sell this stuff. Interestingly, most of the current film merch has OT stuff released in parallel, and that stuff is bought up fairly quickly still, which suggests to me that it isn't just overall franchise fatigue, it's these specific movies. Also the performance of Solo is a clue. To tell the truth, I really enjoyed Solo, yet is was kind of a bomb. Sure, it suffered from a few of the difficulties that any franchise's prequel could suffer from, but, overall, I would call it a very competent movie. I posit that enough people were still feeling let down from their TLJ experience five months earlier that they just decided to skip it.
So, is TLJ widely hated? Maybe not. But I see no sign of it being widely loved.
--Alex