I beat Mario + Rabbids Kingdom Battle a few moments ago. While it is fairly easy compared to other turn-based tactics games, it still offers a decent enough challenge in some fights. But overall, it wasn't too hard. You just need to be careful about the movement and placement of characters. I did die a couple of times (only one game over) because I overestimated the capability of my characters, and underestimated the strength of some enemies. You have enemies that you need to attack from the back, or the sides. You can dash into enemies for damage, and Mario can jump on enemies for damage. There are some melee enemies that will move closer if you attack them, and they hit pretty hard. Some enemies drag you closer, and a few more types. Boss fights were fun, with the final fight being the best in the game. It was in this fight that I got my first and only game over. The fight consists of three phases. I focused the boss, and didn't go for the goons. The only problem is that there are more goons summoned for each phase. On my first attempt, there were simply too many goons on the map. The way I played, it was basically impossible to win the third phase. On my second and successful try, I beat the goons for every phase, before moving on. Much easier, a cakewalk, even.
It was fun enough that I might get the sequel (when on sale).