A remake of the original 2 Super Monkey ball games was a great idea, but the execution and tweaks made mean you're better off with the originals.
The main issue I have is that there were changes made to mini-games that make them far worse than their original versions. Monkey Target, by far the best mini-game from the originals, is basically unplayable due to the physics changes. Others such as baseball have inexplicable changes that you can get used to but are frustrating...why is the friction on the ground so high? And your swing is much slower?
The physics in general for the main game are also different and feel less precise, but to me that is less of an issue than what was done to the mini-games. Some like racing and fight are still fun but the package as a whole is disappointing compared to the originals. If you don't have the originals, this game is still worth picking up used as it's fairly inexpensive (you can probably get it for under $20 if you look)

An all-around excellent 2D platformer, coming up with new ideas in a genre that I thought had done everything there was to do. The soundtrack and controls are great as expected, and the graphics are charming and crisp as we'd expect from a mainline Mario game.
The level variety is excellent, and the main gimmick of each level being a unique "Wonder" event ensures that you are kept engaged each level and you don't feel like you're doing the same thing over and over. Many of the wonders are true "what is happening" moments where you have to adapt and play in a new way for a few minutes, which is usually loads of fun.

The main criticism I have is this game is on the easy side; I have played a lot of this genre, but even the post-game challenge levels are hard the first time but not incredibly difficult; I felt like the challenge of previous 2D Mario games was missing; I'm not asking for the Lost Levels 2, but some entries like NSMB Wii or NSMB had more very difficult content to keep players engaged.