I'm also surprised at the lack of discussion for this masterpiece. Now I know you can (and will) blame me for that, but I've always been more of a responder than a topic starter so if no one is making comments then I'll have nothing to say. Especially when I can be playing Mario instead!
Earlier in the thread, I made a comment about this being the best game within the past ten years as a sort of joke-hype, but I would actually say it turns out to be true. It's way better than Zelda BotW for starters, but I don't think any other game I've played in the past decade has had the same breadth of variety and creativity as this game. It manages to blend new ideas with existing ones such that it feels fresh and familiar at the same time, a culmination of all the best parts of Mario without feeling like a rehash. Mario's movement versatility in Odyssey is the best it's been since Sunshine, I originally underestimated just how well he can get around in this game but after learning the tricks just finding ways to get through a world is fun. Like any game it isn't perfect, but it's every bit as good as the best Mario games of their times.
I wouldn't worry too much at the number of days people took to complete the story, for a variety of reasons. First, it doesn't tell you the number of hours people actually put into it, and second, there are plenty of moons you can't get until you complete the story. To me, the length of the story portion feels the longest of any 3D Mario game thus far, and that wasn't even a third of my total play time so far. If you try to collect every available moon in a kingdom before moving on to the next one, you'll certainly be at it a while.
I think one difference between this and Zelda BotW is the time that the hype had to build. We've known about BotW for years before it actually came out, and it was the first all-new main Zelda game in six years. Conversely, Odyssey was revealed about a year before it came out, though we didn't see much of it until later. And there had been no shortage of new Mario games on Wii U and 3DS. With that in mind, I could see more people rushing out to get Zelda on release rather than Mario.