5 stars: One of the best app to train openings, endgames and tactics. Interface can be a little bit cryptic, especially for openings but once you get used to it, there's nothing better on the market. Tactics are a strong point here, because they tend to emulate real positions, so it's not always about mate in 3 or 4, but sometimes doing the only move that takes you out of the danger.
5 stars: Rated 5 stars because the devs are replying sincerely to all feedback. But one request : The piece moving animations aren't smooth. They lag every time. Please fix this. Edit : Thanks for the reply! But I've installed Lichess too. It's super smooth with no lags and glitches. I can post a video to show the difference between two, if you want.
3 stars: I am a big fan of running through tactics, but the latest update completely broke the app for me. Problem sets are no longer available, the game just hangs on both data and WiFi in multiple locations (in any mode beyond the menu). I have tried clearing cache and data as well as rebooting my phone. This was my most used app, but now it's basically useless unfortunately.
3 stars: I rate it 3 star becuase I truly care for this app to improve. I train on the website mostly, but I find navigating through the app very difficult relative to the website. But overall, the puzzles are great the engine is fabulous, opening trainer is wicked. Just have to fix the little things. I am ready to change the review anytime they improve it well