Pros -
You have improved a lot from the first picture you uploaded using your drawing tablet. So I think you are on the right track when it comes to how you are going.
Cons -
The eyebrows are kinda weird for rainbow dash to have, like what RoguesWolfe said,
Muffins -
I think you should try and draw derpy next and, if possible, to fill out her eyes or at least add a colour around the eye to match derpy's eye color.