Having the underground map feature earlier definitely would have been helpful. Also less stuff locked behind the Aranara quest - they're cute but holy f those quests were easily the worst of Sumeru for me. The Aranara quests were the first time I actually didn't read all of the dialoge because all of these -nara, -bara, -tara, whatevara words made it extremely tedious to follow. As for the archon quest the time loop thingy was sort of whatever, they could have shortened it a bit without making the overall plot worse imo. It wasn't unbearably long, just sort of rather obvious pretty quickly.
Other than that Sumeru is easily my favorite region though. The maps are gorgeous and I honestly don't mind the huge desert, as one half felt more like huge ruin exploration than anything else to me. The surprise inside the sandstorm from the second half is also a truly awesome area and I'm honestly sad we didn't get any reason to go back there after the quest (like big spots of specific resources).
So far my personal ranking from best to worst region is:
Sumeru
Liyue = Inazuma
big huge empty space
Mondstadt
I'm really hyped about how Fontaine will turn out, I'm loving what I saw so far.
Dance Dance Resolution? I fear a rythm game. I'm super bad at those. :( They have thankfully set the bar on those rather low in the past, still it's far from being my preferred type of minigame. At least it seems like it's only one out of multiple different minigames and not the main focus.
As for rewards: I don't need Bennett anymore but he's definitely a top tier reward for anyone who doesn't have him or is still missing constellations. Definitely no complaints here, Bennett needs more love. Also with the Tartaglia rerun next half it'll enable currently Bennett-less people (who also want our favorite toy salesman - I wish all of you the best of luck, he's so incredibly fun imo) to definitely build up international, which is very cool. The ores etc. that they usually also reward will still be very nice and useful for me.