I think this challenge is awesome. It's amazing to see how creative people are and what people can come up with when they stare at a pretty ordinaty bubble. There really are no limits for imagination.

This piece is adorable, I really like everything about it: the concept, the colors, the shading.

Depends how comfortable you are with them. Beginning pixel artists will rely on outlines out of habit, without realizing they often make pixeling more difficult. Where they hinder readability they should really go (right hand, parts of hair). Elsewhere they at least stand out too much IMO: tone them down if you keep them at all. You might also clean them up and use some anti-aliasing where they appear jaggy or thick (eyes for instance). Wherever lines join or cross looks messy and is generally impossible to elegantly fix in small pieces. This is the kind of pixel-level attention to detail that makes all the difficulty and interest of our medium of choice!

Also, voted =)

 -Nyno, thankyou for your kind comments. :) It looks better on white background but yes, it does look washed out here. I think I'll mess with the contrast and add more highlights when editing.

 Thankyou! I didn't know about making ramps (let alone integrated ones) so I will have to study on that. :) As for the 'inside outlines', do you mean for me to remove the dark lines around the hands only or for the rest of the piece?

It's really impressive how well this fit the shape - you did a good job because I don't see something trying to conform to a preset outline here; it looks like the piece just came about organically into the pose it's in.

It feels a litlte 'washed out' to me, like it needs darker darks, especially  the outline. It looks fine okay on a lighter background but the palette gets sapped against the darker grey because of this. I would suggest highlights too on the dress and sleeves, and maybe make the ones in the hair more noticable.

I really do like this piece though - it's really cute and pixeled nicely.

Nice one: great concept and dynamic composition =)

The heavy reliance on 'inside outlines' is hindering you, mostly in the smallest details such as the hands; they're taking precious pixel space that might be better used for shading instead.

Colors are great, but the palette as a whole is not optimal: even though it's not strictly the case, the piece looks like you've made 4 separate ramps (pinks, reds, greys, yellows) instead of an integrated palette (such as explained here). As a result you lack a few more tones to bridge between some areas, for instance hair shadow on the skin.

 So cute

 Thankyou. :D

I love how this piece fits perfectly into the shape for it. Congrats.