I gotta say, it kinda bothers me that some people on dA are so bothered by the 'anime/manga' stuff. It's a valid form of art. I can definitely understand people being bothered by the stuff that's comparable to American kid show cartoons (not to dis those, but I think they're getting more blocky recently), but all of it is valid art. Just like all art, there will be some people that like it, and others that don't. Don't have to look at the stuff you don't like. No one's making you.
Personally, I started drawing when I was really young because my older sister was really in to Anime at the time. It captivated my imagination. The way I learned to draw was through the anime/manga style, and I still like it, even if I don't read/watch Anime/Manga almost ever anymore.
The art style that I tend to look for on art sites, I must say, is the Anime/Manga-Realism fusion. That stuff is to die for. I love it so much. It's got realistic elements, with shading and anatomy, but it still leaves room for a lot of stylization and a lot of imagination.

And even if we're talking about the blocky American kid show cartoons that I criticized before, that's valid art, too. Anything can be valid art. Do you enjoy doing it? Could you spend hours on it? Do you do it because you want to? Does it take skill? Did you put effort into it? Does it MEAN something to you? That last one is the most important part--does it mean something to you? Something can only be art to a person who sees meaning in it. That's what art is. And as sad as I am to read the comments of people who say that they see Anime/Manga not as a valid form of art, I must admit that they are valid... to themselves. Art is relative.

So, when you ask if something is worth it to put effort into, you should only ask yourself. If you're asking this question because you are not sure, then you must either come to your senses and realize that you love what you are doing and should no longer doubt it or come to your senses and realize that you are ready to move on.
Either way, I hope that you continue to put your Art up here on deviantART. If you enjoy it, you shouldn't worry about if other people like it or not.