I will start this off by saying that Super Mario Odyssey is a great game, and it is certainly worth your time. As a long time fan of the series, however, it doesn't feel all that new and fresh. Perhaps I'm being unfair when I compare it to The Legend of Zelda: Breath of the Wild, but they're both the most recent main entries into Nintendo's two most loved series, so it's a little hard to look at one without being influenced by the other. I did not play either game until this year, which I have completed both around the same time, so that prospect seems even less possible with them both ingrained into my recent memory. That being said, I have some praise, and some problems, that I need to express for this game before writing a review for the other.
The gameplay is fairly standard for a 3D Mario game. It controls very well, with all the tricks and techniques from previous games put together in a way that makes sense and feels good to play. They've added a few things, most notably the hat mechanics and a roll ability. The hat (a sidekick to Mario named Cappy,) mechanics are crucial to the game -- being able to jump off of your hat and capture enemies makes getting moons (this game's version of Super Mario 64's stars,) solving puzzles, and doing basic platforming interesting and fun. There's a lot of variety to be had here, and the different enemies are all really fun and unique to control. There are a few sequences that feel a bit repetitive, and a few areas that feel a little too long, but nothing major. I do take issue with the sections of the game where you just play as Mario, though. Most of the game plays very similarly to previous entries in the series, and while that gameplay hasn't quite gotten tiresome, I do feel that it's towards the end of it's course. I would be surprised and a little disappointed if the next Mario game plays this way. While I do think that Odyssey is the better game, I loved Super Mario 3D World. That game had a unique structure and had a great fusion of classic and modern gameplay that felt more unique and fun to play than this entry. There is definitely more spectacle and better design in Odyssey, but I had less fun in many areas.
A lot of the levels are very good and designed really nicely, but a few don't really do it for me. New Donk City is a really strange addition to the game, which I really appreciate, but the gameplay was lackluster. You do the same thing you did just an area or two before, breaking up the introduction of new mechanics in a way that I didn't care for. I blasted through that level and many others because the game puts you on a linear romp from point A to B until you beat the bosses. After that, exploration can be fun, but the huge quantity of moons almost dissuades one from trying to collect them all. Many areas (almost all of them) have over 60 moons to collect. That's just way too many for me! My desire to 100% a game falls off pretty hard around the 100-things-to-collect range, and this game has almost 1000 moons. I can't do it. I have similar problems with Breath of the Wild, since there are 900 Korok seeds. It's too much for me, personally. Maybe this game hits the exact right spot for you, though. If it does, I'm jealous. I wish I could get that much out of these games.
My three most major gripes with this game are it's music and it's bosses. The music is mostly forgettable, (with a couple of exceptions like Steam Gardens,) and a few tracks have vocals, which I really did not like. They're pretty major moments in the game, and they kinda fell flat because I just did not like the songs, not even a little. The bosses are the biggest let-down, though. Most areas have one unique boss and then a repeat boss. This leaves half of the fights lackluster and usually very easy. You can use the same strategies in most cases, leaving the second iteration destroyed with little effort mere seconds after the fight starts. It's a puzzling decision for a 2017 game, but it's Mario, not Dark Souls. The bosses are almost never the highlight for these games (except maybe the Super Mario Galaxy series.) The unique bosses are pretty good, and utilize the mechanics of Cappy pretty well, though, so it's just a mixed bag.
Overall, it's worth playing and beating. There are a few awesome moments that made it all worth it for me, but this will be the first console Mario game since Super Mario Sunshine that I do not 100% complete. The game is designed for everybody in a way only Nintendo really nails. It's not too hard, not too easy, not too intense, and not too boring. It's just right. If you have a Nintendo Switch and you don't own this game, I don't know what you're doing.