F2P friendly, kind of. It's more of you need a lot of game knowledge of its features and patience to succeed as a non spender. You need to be able to tell which events are good for you to spend your coupons on, which resources are worth hoarding, and what ninjas are worth spending towards.

Is it friendly for F2P? I'd say generally not. You have to have extreme patience because the things that everyone wants are items that require months of saving coupons for. It also requires a lot of work and you need to be able to do most of the evening timed events if you want to get anywhere.