At this point, probably about 300. I've had since the day it came out, and have been playing it at least once a day, or once every other day since. On my main account I am at level 49 with an S+ rank, and on my brother's account, which I use as a secondary account, I am at level 24 with an S rank.
I'm still amazed how much I been dedicated to this game, but I think it's just that fun.