There's actually a lot more here than just the fanservice. Yeah that's a pretty big part, but a lot of the game are these surprisingly well written visual novel parts and the core cast is surprisingly deep. The hanzo girls especially all have their own insecurities and issues that they're dealing with on top of being ninjas in training that really adds to the experience. Hibari's massive inferiority complex in particular does a lot to elevate her character beyond just being "the dumb one". The Hebijo girls aren't quite as fleshed out in this game, but Deep Crimson would help with that. The gameplay is also pretty cool for a 3DS game. It's this frantic, air combo heavy, 2D beat em up that's almost like a side scrolling Dynasty Warriors. Even with the frame rate issues, I honestly think this game feels the best to play out of the series.