Is this worth playing for someone not familiar with One Piece?
As a fan of One Piece, it's difficult to be objective, but I'd say the game has a lot going for it besides the One Piece IP. The UI is easy to navigate. The visuals are amazingly consistent. I haven't played many mobile games, but this game has the highest production value I've seen so far on an Android platform. The attention to detail in the sprite work reminds me of games like
Metal Slug, and the character portraits are some of the best One Piece art I've seen. Can't believe I'd say this about a mobile game, but I'd buy a $30 art book.
The gameplay has a nice sense of "oomph" to it. You hit the screen, your guys smack stuff around. It hasn't gotten old yet, and I've probably put over 100 hours in. I find it far more engaging than card battles or any of that other stuff that involves shuffling static character portraits around.
Problems, well, on Android, the sound effects and music cause performance to choke on slower devices. It's not as bad on iOS. Like other games of the genre, it leans heavily on the RNG, leading to heartbreak when trying to get new characters, and slower progress through higher-end missions.
I'd just try it out. You'll know pretty quick whether you're into it after the tutorial stage. The game doesn't change drastically from the way it starts, really.