Beat Sunshine and am getting close to 100% completion with 101 shine sprites. I enjoy the game but I now can see why it is often seen as a sort of black sheep within the series. It can be incredibly challenging, sometimes as a result of strange design choices. Mario feels a bit slippery, and there are quite a few areas that require precision platforming which can result in a fair amount of do-overs. There are still some areas that I am not sure how I can get an objective done because the way mario jumps and moves cannot reach the desired goal, making it seem practically impossible. When throwing or grabbing, the game sometimes doesn't register the action leading to repeated attempts (ex. Giant blooper tentacles won't be grabbed and fruit being tossed at odd angles) It can oft feel unfair after repeating a challenge over and over but failing due to the game not cooperating. Sometimes the outcome can be random, for example there is a stage that requires being tossed by piantas that neccessitates trial and error as you have to speak to them in specific locations, angles, and at the right time. Once you are tossed, there is no changing your trajectory, and you will fall into the void if you make a slight error. Then there is the infamous pachinko stage and the poison lily pad stage. The pachinko machine can be managed if one hovers right after hitting a peg, but the game doesn't allow much maneuverability in this state, especially with the top left coin as it automatically shoots you up to the right, and attempting to float back left only leads to hovering in a still state. A good portion is left up to chance and incredible timing. With the lily game, you only have one attempt to obtain all the red coins as you are being moved one way through the course, there is no way to go back and correct a mistake.
The blue coin challenge is also bordering on the excessive, with 240 coins scattered throughout the courses and no real indication of where they are (there is fortunately a number tracker on the map of how many were found in a given area, so you can compare with what you have and how much there is supposed to be).
I have some qualms with the game, but I find it creative with many varied challenges. It is a beautiful game, but I personally believe it could have been handled a bit better. I wish it could have gotten a remake or a sequel to expound on some of the ideas there which have never been in a mario game since and improve upon it. As it stands so far, I like it but it is one of my least favorite 3d mario games out of the five. That said, it's good and certainly worth a shot.