Since you asked my opinion going to submit is as a critique, hope you don't mind
I will start saying the things I like:
First of all: I like how you shaded her hair. I tried that on my drawings, I don't think I got a good result, but you made it look perfect!
2nd: I also think the eyes are, they're usually really hard to do, and you good them perfect!
3rd: Linearting is almost perfect! The lines are really soft, however It could be better If you use a bit the pressure tool on SAI, They make the lines more soft and pretty
Also there's some things I don't like:
Her jaws and chin looks a bit wreid If you know what I mean Maybe trying to make it a bit more pointed?(it's how I think how to say it in english )
The Nose is kinda too away from her lips, try to do closer
And the blue hearts are on totally different sizes, I know they're hard to keep in the same size so I guess I'm not the one to talk XD
Other than that good job! ^^