Hey hey hey, you can't go stealing my name like that!
You're the second person I know of that started pixeling this year. I myself started getting serious this year too
Anyways, the critique:
Your tree is pretty good!
A pattern I see is that every light-colored mound has a dark line inside. I guess this was done to imitate the dark middle part of individual leaves?
In the dark part of the tree, though, the opposite is true: the lines inside the blobs are of a lighter color than the blobs themselves. Maybe they should be darker as well? To be consistent with the other ones? Don't trust me on this, it might end up worse
The three or four pixels floating around are to give the feeling of branches that aren't completely covered by the leaves, but I think you should make these "holes" a bit bigger. And, maybe use a darker wood color, because those two wood pixels on the left probably wouldn't have a direct source of light.
The outline on the upper part of the tree is of a darker green, but the one on the darker part is the same green, that is, non-existant. Try outlining it with a darker green to see if it looks better.
The upper-right part of the tree is a small transition between the light and dark parts, but because it has less colors than either of the two, it looks as if unfinished, sort of. Maybe use the dark green to shade a bit, but not as excessively as the dark part.
All in all, it's pretty good. (Had trouble looking for flaws
) It sure doesn't look like the work of a beginner