Koorinchan
Example : "You don't have any talent and your work is such a BS! It's a piece of trash... nobody should read it" <<< BIG NO NO!
"Nice manga, I think you should work on the proportion more since it seems kind of off a bit there. Hopefully you'll improve more in the future wink " <<< very much acceptable since it pinpointed where or what to be improved.
I'm not liable to flame or anything, but sometimes constructive criticism won't come with accolades.
Hopefully also not with outright insults though, I agree with you on that. Politeness is always good.
Um... question though... actually, two.
1. Why so much Japanese? Are you fluent?
2. Why are you putting it on deviantArt? It's kind of hard to go from page to page. That's why I stopped uploading one of my old comics on there, and never really went back to doing it unless I had, like, one-off strips, or old regular art, or something. There are a number of comic hosting sites which would possibly make it easier for people to browse your pages, and also easier for you to upload them (categorizing on dA was always a pain for me).