Don't let the "visual novel" bit turn you off. The story is fantastic, and plays out as more of a graphical adventure, although very, very simplistic in mechanics. The characters are interesting and fleshed out. There's more of the tower defense / battle bit than I expected. It's a perfect balance so far of "gameplay" and "story", where neither is too brief nor drawn out, and the story bits are captivating so far. I'm about 2 hours in and enjoying every bit of it. I haven't mentioned the obvious. The art / graphics / animation are pure Vanillaware goodness, and the sound and music... sublime. An audio / visual feast. And to top it, Atlus as the god-tier publisher.
The bonus artbook is a nice touch. The game comes in a standard case, with it and the artbook encased in a slip cover.
Worth it.
Edit and update: 25 hours in, and omg. What an amazing story. I am NOT a VN guy, and my days of graphic adventures were decades ago, but my goodness. I'm actually at a point where I've advanced the story so far I need to catch up on the tower defense bits, which are normally more my thing. This game is something really unique that I'm not sure has ever really been done before. I just wanted to update, as my original glowing review was after 2 hours. After 25, I can say that... WOW!!!!