Yeah, it's Good. Great UI and (optional) assist features, with a ton of puzzles to solve.
The techniques that the game tries to teach you are very helpful, but it may take some trial and error to fully grasp some of them. The game's hint system will always show you a technique that can be applied to the puzzle's current state (assuming it's still a valid board), along with an annotated description, but this same system is also used for the game's tutorials. As the techniques become more difficult, you may need to go through a decent amount of examples until you can recognize whatever pattern they're trying to show you in a real puzzle. Some of the hardest techniques feel so esoteric that even just solving their tutorial puzzles can be a challenge, let alone making use of them in an actual puzzle.
Also, as of writing this, it seems like some of the achievements might be bugged. I'll just say, if you're a completionist, don't stress too much about doing the 365-day daily puzzle streaks. I finally got them done after several broken streaks, only for the achievements to fail to pop. That said, if the game wasn't this Good, I probably wouldn't have kept at it for so long.
The techniques that the game tries to teach you are very helpful, but it may take some trial and error to fully grasp some of them. The game's hint system will always show you a technique that can be applied to the puzzle's current state (assuming it's still a valid board), along with an annotated description, but this same system is also used for the game's tutorials. As the techniques become more difficult, you may need to go through a decent amount of examples until you can recognize whatever pattern they're trying to show you in a real puzzle. Some of the hardest techniques feel so esoteric that even just solving their tutorial puzzles can be a challenge, let alone making use of them in an actual puzzle.
Also, as of writing this, it seems like some of the achievements might be bugged. I'll just say, if you're a completionist, don't stress too much about doing the 365-day daily puzzle streaks. I finally got them done after several broken streaks, only for the achievements to fail to pop. That said, if the game wasn't this Good, I probably wouldn't have kept at it for so long.