Absolutely, finished reading just now and the one thing that didn't stop bugging me - although I very much like a lot of aspects of this series - was that Ivan neither seem like nor look like Ivan any more.
It's one thing to develop and evolve as a character, and it's another to loose your character. Sadly this has happened to Ivan. What once was so fun and appealing about him is no longer.
I had to go back to check to confirm but you're right. Ivan definitely had that hard edge look, but also Hen wasn't always stuck in round chibi chicken mode. His face is now almost exclusively drawn round and comically while back in the result chapters, he looked like his own person. Wow, I'm kinda mourning a little...
Edit: early* chapters
Yeah, he suffers from Puck-syndrome, as I've begun to call it (from Berserk, if you're unfamiliar. He began as a serious character, but now he is exclusively used as comic relief, and only looking like a little onionhead.)
I gotta be honest, I find it a shame how much the artstyle had changed Ivan's appearance. In chapter 1 he started out as this older, scumbag and maffia looking man and I loved that he looked so different from everything else. Now he looks way younger and pretty boy-ish. It makes more sense with his personality though, but he went from daddy to boy nextdoor.