You know what I really like about this software,the interface is user friendly.The brushes also almost as smooth as in Sai and we can later edit the picture like in photoshop and surprisingly the software is very light unlike photoshop XD.
and the most important is
IT IS FREAKING FREE OF CHARGE!
PS and Sai already expired?no more worry cause you can always download Krita.
(a/n: i am not their saleperson..haha..im just sharing this with your guys)