In my eyes, Gen 7 has replaced Gen 5 as the new most controversial generation. I have praise, but I'll start with criticism first.
The year Sun and Moon released was a massive high for Pokémon. People who hadn't touched the franchise in a long time were suddenly very hyped for it because of Pokémon Go. I know several people personally who were excited to play the newest installments releasing that coming fall. But when they finally arrived, most barely finished the first trial, if that. The games were bloated and didn't resemble what they were nostalgic for. Meanwhile, more dedicated fans were still perturbed by the lack of content from Gen 6, and were waiting to be wowed again. For many, these games didn't resolve those issues either.
Everyone knows about the dialogue and pacing issues. But if you can accept that these games are talky, I think there's a lot to appreciate. I think this generation provided Pokémon's most vibrant region, and a dex more tailored for its habitats than any other. They're stylish, immersive, and were a nice mix-up from what fans had become accustomed to. But for some, too different to rank alongside the games that came before. At this point, I'm left wishing there was less talking and more showing. More exploration of Ultra Space, elaboration on Fallers and a plot more designed with them in mind, and a more meaningful conclusion to Rainbow Rocket instead of just being a cutesy inclusion. But I don't think those things take away from the 3DS era's impressive art style, which peaked with USUM.
And speaking of USUM, to this day these games feel the most "complete" of any game out there. Z moves are probably the least liked of any gimmick, but their inclusion alongside Megas means a game with 2 battle gimmicks and over 800 Pokémon. Bottlecaps *finally* let you fix IVs so it felt like a good final destination for team members who had been struggling in battles game to game. But I do think some more side content like contests would have been nice.
If they ever revisit these games, for the love of god let the main characters stop smiling once in a while. They deserve a break.