I liked the casino side-quest once they got there. Set us up for the ending scene which made a great ending imo. Could have maybe been 15 minutes shorter, but I was not bored once. Expected the scummy codebreaker to be the actual codebreaker, take off his jacket afterwards and have a tatty flower on his lapel after all. Wasting Snoke was unexpected and brilliant imo. Agree that Leia was wonderful. Kept trying to see if they cgi'ed her face anywhere and could not detect it. Wonder what they'll do in the next film, cgi her altogether? I'm betting she has a minimal role in the next film so we're not too distracted with feeling creeped out that that's not really Carrie.
The problem with the Casino side quest is that it never went anywhere in terms of moving the story. The only thing it did was to bring Finn and Rose together, but you could do that a lot of ways that don't involve a huge side story. Their gambit failed, and a lot of people died. Of course, they could make it meaningful depending what they do in ep 9. E.g. Benicio del Toro could be the new Lando, or the kids they inspired could do something important. If they don't do something that brings relevance to that 30 minutes of screen time, I'll be vastly disappointed.
I'm convinced that the kid is going to have his own spin off movie in the next decade and introducing the character is the only reason they shat out the needless casino story line. I thought it was a good movie for the kind of movie it was but I would have liked it A LOT more if the casino story line had been dropped and if the imperial guardsmen hadn't bopped around and assumed Teenage Mutant Ninja Turtle poses.