A suitably magical soundtrack and strong voice acting throughout, Forgotton Anne sounds lovely...
...but it looks far nicer. The handcrafted Studio Ghibli-esque art style is superb, and about as close as you can get to playing a proper anime (apart from all those Dragon Ball games and that).
Neat puzzle mechanics, patchy, but mostly robust platforming, and a nice MacGuffin in Anne's Arca gadget make Forgotton Anne an enjoyable experience, save for the odd frustration here and there.
A fairly generously proportioned game, a lot of effort has clearly gone into Forgotton Anne. And once the credits roll, you're free to explore its enchanting world, traveling to previous areas to scoop missed collectibles and experiment with different choices.
Only the collectibles are available to see on Forgotton Anne's list. The rest of the game's achievements are hidden, so you'll have to work them out for yourself from the descriptions. Spoiler: there's one for completing the game. The rest seem fine.