You could always just use it as reference for a more improved version.
I definitely dig Geo7877's pose, and I think it's because it's got good gravity (not to mention accurate musculature). The body's down lower, the arm's up higher, and he looks like he's going to pounce on you.
When people first start to draw bodies, they tend to deemphasize the overall energy, but it's necessary to emphasize the energy instead, paying attention to how the body tilts and all. A drawing doesn't have to be detailed at all to convey energy. I'm currently drawing a comic that utilizes Chinese brush painting, which simplifies everything down to a few brushstrokes, and I really like
this artist's work (even though he isn't Chinese

) since he
captures the tension and energy without making anything too detailed.
As for your age, yes it's pretty good, but you can't let your age fool you into thinking you can't be better.

Also, most people can't draw for crap, so you're really ahead of the game! That's why I think I need to be somewhere where people are super-talented, so I can be properly pushed.
Also, you don't need to buy anatomy books. I went out to the library and found a book on animal anatomy, and stayed after work to copy all the pictures out of it.

Of course, since you're 15 you might not have access to a copier like I do, but hey, 5-10 cents a copy won't kill you.