The game seems decent enough. All but the silver rolls have a 3% chance at a 5-star general. The real question is how many of those rolls you'll get without having to whale. If it's like Mononofu, they'll give you enough that the game may be dominated by whales for a couple of months, but then the free players largely catch up after that. By the time Mononofu shut down, I had a level 55, 4-star version of 29 separate UR generals, and that's after paying about $5/month on average while I played the game.

It looks like once you get a general, getting her to the max evolution level is pretty cheap. You won't need five of the same card like you did in Mononofu. The real questions are how hard it is to get one, and whether there is some other essential resource to power up that's much harder to get.