The character design is actually not great at all (although it does evolve throughout the series, just like the old garfield and new one, or the old simpson and new ones, still the same, but a little more refined), but it's the personalities and the story that make them feel alive anyway. There has been a 2 episode OVA on this manga as well, but sadly they never got any further than that.
I really would love to an anime of this as well.
Having had a phase myself when little children would just start crying at the sight of me, it is also really easy to crawl into the skin of kitano seiichirou. By the way, that problem does not occur for me anymore... Not as much anyway, now it's mostly like "look, that man has long hair" and in some cases still a frightened look, but nothing more... Luckily it's not bad enough to be seen as some criminal, to most adults I apear as friendly and cheerful, eventhough I am actually suffering from depression... Ehm... Wait.... The manga, we were talking about the manga!
Hehehe, so anyway...
You may have noticed by now, the main character is a scary looking guy that soon becomes known as the devil guardian due to a streek of misunderstandings, because in fact he is indeed a very kindhearted young man, trying to fit in.
I have had a lot of laughs and a few sad moments too while reading this manga, it really is very well written and has a nice flow. I just flew through all 15 volumes/84 chapters in 3 days.
And that for someone who actually dislikes reading because I make too many mistakes slowing me down. (I actually read faster than my thoughts can handle, mixing up the words I have 'seen' and the ones I actually understandingly read. But that's more personal details about my ADD and stuff, so let's skip that. =P
So, if you like the delinquent settings, a little roughing up, lots of misunderstandings and funny situations and a lot of characters you can't help but come to love throughout the story, you can't skip this manga.