It's okay. I think it could have been named better.
I understand their reasoning for not having a downside as part of the main mechanic, but at the least I would have expected more cards to add a downside. Like some powerful mythic with a really strong effect whenever the Ring tempts you, but when it temps you for the Xth time you lose the game, something like that.
The mechanic is very nice flavor-wise and fine as a mechanic but it doesn't scratch any of my MTG itches. I'm a fan of combos and engines, and the mechanic does not lend itself well to that play style.