Is my artwork good?

is my art work good? If not how can I improve? It's just well I don't knwo whether it's good for my age or not... it very hard to tell. Im 15 by the way! I'm no artist this is merely a hobby, but I'd like to imporve all the same!
I have more examples...

on my profile if youo need them...

I think its exellent :D I'm the same age as you and I can't draw this good, so yeah... its a pretty great drawing (It actually doesn't really depend on your age, just your skills) I don't think it needs that much improvement, although around the eyes could use abit more detail e.g. eyelashes could be more spread out and maybe you could make the eyelids abit more noticable and you could use a darker and lighter shade for the eyes to give them a more realistic look I'm no expert either lol but this is what I usually do. x

It seems you have a good eye for balance... asymmetrical and tonal. The only encumbrance in front of you is meeting your mind's eye. This can only be accomplished with repetition. Finding your influence[style] and exploiting it in your work. It is good. Keep it up!