Tristan-I can't explain it!- but him and every other character just seems so REAL. Like, you hit their personalities perfectly, it's so great it's unexplainable!
The plot makes sense, you don't write random things to try and make your book funny or whatever. (Though sometimes you do go off topic, but it's in a nice way -like with Mai's fashion show:)).
Things aren't rushed, and you have nice long and cute chapters-which I always enjoy.