I wouldn't say it's popular, but it does OK in America. Well some of the titles. Many have flopped. Most anime fan don't like it because its "not authentic".
The only one I was ever a fan of was Shutterbox, but Tokyopop cancelled that before it was finished (only published 4 out of the 6 volumes planned). I keep track of the artist, however, so if/when she ever does finish and release it with another company, I'll buy it there.
I can't speak for Japan.