So let me get this straight, you happened to be a young swordswoman who is traveling across Japan with a fox demon of some sort in order to find her dad while killing other demons possessing common household objects. I guess that sums up the basis of the story. I don't remember how long I have spent with 99 Spirits because I mostly played it offline when my internet was down for a period of time, but I still have not finish my first play through so keep that in mind.
The combat system pretty much consists of guessing a word through hints given to you when you attack the enemy and after you have successfully guessed the word, you are able to kill the enemy or capture the soul when given the opportunity, but guess the word incorrectly and you will take damage with no chance to negate it. Other than that, it is really just a QTE. In theory, it sounds like a good idea, but in practice, it gets repetitive pretty quickly because you are guessing the same enemy over and over again due to the limited enemy variety in each region, not to mention all the enemies feel very similar to one another. The boss fights completely enforces the idea of sitting through QTEs because they behave just like the normal enemies you have faced for the umpteenth time except they have maybe 10 to 20 times more health, has the ability to kill you in maybe 2 hits at most throwing in unblockable attacks every so often forcing you to stay in the defense stance around 80% of the time, and heal very frequently to extend the length of the battle. The movement for the world map is pretty standard with nothing special to make note of except for the hunger meter that does nothing except makes moving around the map slower than normal. Even if the hunger system did something to impact the game, it does not tell you what it even does and even if they do tell you, the game does a pretty bad job at it.
The soundtrack is, in my opinion, ok at best, but the battleground music can get really repetitive sometimes and you can even hear the where the track loops.
Perhaps the worst offender this game has is that it crashes very often if you don't know what is causing it to crash in the first place so if you are going to play this game, I suggest you head to the forums to look up on other people's experience so you hopefully won't have to deal with them too much.
I am really having a hard time on whether or not I should give a recommendation for 99 Spirits because it's game play feels lackluster in some areas in addition to the frequent crashing and a fairly iffy story, but it has an interesting idea with the combat system despite on its shaky execution and has some fairly interesting characters to meet. For $15, I think it's a hard sell for those who are skeptical about the gimmicky combat system, but if it goes on sale for maybe $10 or less, it's possible to take it into consideration. At the end of the day, I can't recommend 99 Spirits despite that fact that I had a decent time with 99 Spirits due to all of the problems I have stated before, but then again, it's probably a game that is best played in short bursts. If you do happen to take an interest in 99 Spirits, try the demo first before pulling the trigger.