This took awhile for me to beat, not because of its length, but rather I kept being discouraged by the level design in the later stages of the game.
All in all, a very solid metroidvania with mediocre linear progression (especially compared to Metroid Fusion, which I think nailed Linear progression), but still functionable enough. What holds up the game is the fantastic bosses and mechanics. What I really loved was how the game emphasizes using the Slow Mo, Time Stop, and all of your abilities in fluidity and it is great fun! I just wish some areas were a bit more thought out, but the game is worth a play, Touhou fan or not.