It starts off well, but repetitiveness and awkward controls means Kororinpa falls at the last hurdle.
The premise is pretty straightforward, you roll a ball along increasingly challenging levels until you reach the goal. Along the way, you have to collect red gems in order for the goal to open up. This is where one problem lies. If you miss a gem that's near the start of a stage, but you're right at the end, you pretty much have to fall off the edge and start at the beginning of the level again. Thankfully there are unlimited lives in this game, and levels are pretty much based on how quickly you can complete them. There are also green crystals hidden in each level, which when collected unlock bonus levels for you to try. These are usually in very hard to reach places, and require all the patience of a saint to retrieve.
The motion controls to begin with work really well. The ball responds accurately to the way your wiimote is pointed, and it's not too slippery. However, as you get on to the more challenging levels, you'll find you're having to bed your wrists into places you thought were impossible to do. My wrist actually started aching from doing this too much, and when you're having to constantly rotate the wiimote, the ball suddenly becomes unresponsive, and you might even end up falling off the stage because of it. This becomes annoying very quickly. The camera doesn't help much either. Sometimes, a part of the scenery will obscure your vision, meaning you'll most likely fall off. This doesn't seem to happen all too often though.
The graphics in the game are good, but nothing special. Everything is detailed enough, but there isn't really anything that stands out that makes you say "wow!" The sound, also is pretty average. There's really no memorable tunes to think of, although they do try to set the mood of relaxation and calmness to the game, which does work.
The biggest downfall of Kororinpa is that it is an incredibly short game. You could easily breeze through all the standard stages in the game in one sitting. Sure, there's a mirror mode upon completion, but that's basically something the developers slap on to increase longevity to a game, which I personally don't like. There are a number of different balls to choose from. Some are slower and easier to control, while others are heavier and move faster. But really, play a stage with one ball, and you've played it with all of them. The only reason you'll want to replay the stages is to obtain the green crystal if you haven't already, or to try to beat your fastest time. Naturally, this can become repetitive pretty quickly.
In short bursts, Kororinpa is an enjoyable game, but thanks to awkward controls later on, and the shortness of it all, you'll most likely be looking elsewhere for fun sooner or later.