The rendering is definitely very nice and 'comfy', but the perspective is jarringly distracting. It looks very wonky.
The issue is that there is a severe disconnect between the extreme, warped perspective of the top of the tree, and the normal perspective of everything else (ground, back trees, clouds, etc.). In other words, you've applied an extreme fish-eye perspective to the tree (and only part of it), and the result is that you're not getting that "looking up at a tree" impression that you're obviously going for.
The solution is to distort the perspective of everything else to match the the fish-eye perspective that you're going for with the tree. Pic related is a hacked-together solution to give you an idea of how the rest of the drawing can be distorted. A big part of this is to decrease the size of the tree trunk as it gets farther away from the viewer, as to suggest it's going back in space (which yours currently does not do despite the extreme perspective).
A cohesive perspective is tricky to pull off in such distorted perspectives like this, but it's really necessary if you want to get the effect of looking up at something like this. Hope this helps!