It's a solid game, but the cash shop kills the experience for me.
You balanced the game so each player almost has to use the cash shop. Most of the missions require the player to buy at least one item. While you can buy the equipment you need without the cash shop, it takes a ridiculous amount of grinding, and you're usually over-leveled by the time you can actually buy it.
For me, the best option is quitting. Grinding ends up being a Sisyphean task, and using the cash shop to buy the equipment and quest items i need to continue the game leaves a bad tate i my mouth.