I like how drawing and photography was used at the same time. Although this was tried a lot of times, the fact that both types (photography and pencil drawing) can be used helps widen the possibilities for a design.
This pin is similar to the first pin, it has those fine white lines that show the proportion of the bird. I like how it shows the original image and then it transforms into a pixelated bird. Low poly, looks like a fun or frustrating exercise to do.
"Vertical Landscape" by Eiko Ojala. It looks like a paper landscape but the artist actually works digitally and hand-draws all the elements to look like they're cut out of people. (Hint: the shadows help!