The people who rated value higher than 1 are smoking. After a certain point in the game almost any form of progression takes premium currency and takes quite a bit of it. It comes very very slow as f2p. I can't even imagine the type of person that would spend 50 bucks for 10 roll on a simple near eventless idle game.
Pretty fun, honestly. The PVP element is reserved for whales, but as long as you don't take it too seriously it's a nice time waster while you pop a squat at work.
Personally I really like the art and the Labyrinth allows you to play with characters you don't own, so it's really fun for F2P players like myself. Basically just find the character you wish you had and pretend you do! I don't know any other game that lets you use characters that you don't own, to get rewards for the ones you do lol
Progress does slow around the start of the double digit chapters, that's true, but tbh that shouldn't matter? It's AFK Arena, not MMORPG Arena, temper your expectation on a free game with continuous updates.