I think it turned out really well. It started out being Prime, but the shape of the eyes the first time I drew them made me think of an evil character, so I changed plans and went for Megatron with a mouth plate. It actually also reminds me of Star Saber.
As a user of MSPaint generally by necessity only (as I hate using it otherwise), I would say you did a fantastic job.
That takes a lot of patience and skill. I hate using computer programs for art period, aside from coloring. But you seem to be very proficient with a mouse
MSPaint is actually pretty easy. You have the pencil tool for sketching stuff out and the erase tool to shape it up. For coloring, you again use the erase tool. Choose the color you want to put down for right mouse button and the color you want to replace with the left mouse button. Then just use the right mouse button to draw. The right mouse button's color will replace the left mouse button's color and affect nothing else. It almost feels like coloring using Copic Markers, but without the stress of messing up by going outside the lines or layering it on too thick. The final trick I used is I only drew half the face. I pressed ctrl+a -> ctrl+c -> ctrl+v and then mirrored the image, while making sure the right mouse button's color is white and the selection is set to transparent. Beyond those fancy tricks, the color picker tool, zoom and the selection tools are your best friends for getting everything just how you want.
