I've played it and all the titles before it, and it's my favorite so far, with the GBA and DS ones tied in second.
It's definitely skill based if you're aiming for online top rank and/or best time attacks.
The new tracks are beautiful and creative imo, and has my fav selection of retro tracks.
The karts and items work very smoothly.
It does have its obvious flaws however. Missing Waluigi despite having a track based on him, everyone looking like badly modeled plastic toys (which I guess is somewhat homage to the original Mario Kart?? likely coincidence), and the lack of VS is absolutely the biggest flaw. It also continues the flaw of every MK game in which Battle mode has no trophies, but eh, someday right?
But overall, again, I love it. I love that you can play it in 3D. I love having Peach's castle as a course, cheep cheep beach, Pirnaha Plant Slide, the music course, Wario's shipwreck, and Neo Bowser City come to mind.
I love the underwater and flying gimmicks too, they give a nice change of flow to the game.