Holy hell, this is badass. I love it how Armored titan has no prepared stance (looks like he thinks he can charge and attack whenever he pleases) while the rogue titan's taking a more cautious/prepared stance, deterred but still determined to take him down, despite the obvious difference in strength.
Your brush technique is magnificent, they have that natural/rough look, yet they blend so well in the end. Even things as intricate and detailed as muscle look great.
The solid blend of light and dark shades also gives the titans depth, which is another thing I like about your style. I like how the armored titan has a subtle shine to his skin (?), making him look as if he's wearing a suit of armor of sorts. Badass.
My only gripe is that the background lacks some detail compared to the titans.
Regardless this is an awesome piece. You did the series justice.