what the? that's not a fail. You're such an artist being all..self...doubty...that's a word right? you know what I mean! Don't forget, all art hits that "argh I hate it!" point. I reckon you could give that another hour and polish it right up ^_^
Either way, it's looking pretty freakin' sweet if you ask me.
I love this look in art. On the boarder of realism and cartoons. Very realistic texturing on top of line work just shy of a very charming charicature. Im reminded a bit of The Adventires of Tintin. Thats a good thing.
I actually feel like your version is little harsher than the painting. After studying it a bit, I'd say that's because her eyes and brows are a lot closer together, and seem to have less face beside them. At least one eye width apart with a half an eye width on either side is a good practice, even when stylized. Also, her collar is a bit stiff. The original art goes up and over her shoulder. Besides those very small issues, though, it's an amazing likeness. I especially like what you did with the skin texture. And it may be small, but I think you did a wonderful job getting the shape of the brows right. The eyes have great depth and luminance. Kudos on awesome work!