[Espy]

Will be going into somewhat-unimportant details, so feel free to ignore...Also, don't get discouraged. I just critique a lot.

1.) "Good" is relative. I wouldn't know what you mean by "good" unless you provide some sort of reference to something else.

Anatomy stuff:
2.) Torso: One boob seems to be a bit higher than the other. /awkward. Also, that is a very narrow waist compared to the shoulders and hips, but maybe that's just my preference for people of normal body...structure. I can't find the right word.
3.) The neck's a bit too far forward at its base. And unless the head is really tilted back, the neck wouldn't be that far back, either. Even with the current pose, it seems a bit strange, but not too far off.
4.) The elbows are a bit high up. You want to have them at the waist, usually, around where the hip bone starts. (Use yourself as a reference. It helps.)
5.) The two lines making up the collarbone are a bit wide. Just saying.
6.) She needs some muscle on the underside of her (right) arm, too.
7.) It kind of looks like she doesn't have a ribcage on the right side. If she's that skinny, you'd be able to see the bottom of her ribcage jutting a bit against the skin (no need to draw the actual ribs themselves, just the shape of the whole ribcage) before it tapers down to her stomach.
The chibi:
8.) The head should probably be a bit flatter/shorter and rounder for a more chibi-esque feel.
9.) If you changed that, the eyes should be moved relatively lower.
10.) Arms are a tad long for a typical chibi.
11.) Torso's a bit narrow for a typical chibi.