I've probably said this a few times before but that doesn't make it less true, micro-scale builds are extremely challenging because you have to distill everything down to its most basic essence. There's no room for extra details.
And that's exactly what M<0><0>DSWIM ! has done here with his micro-scale Avengers. Each of the figures is instantly recognisable despite being built out of only 20 or so small LEGO pieces (okay Hulk gets more, but he's Hulk.)
There are no facial features and no logos but you still know who everyone is.
Source: MOCPages - Avengers Assemble!