I've found manga that has less than stellar artwork harder to get into perhaps since a strong visual appeal is a great hook. But if there isn't a good story, even the prettiest series can have difficulty holding my attention over the long run.
Definitely good story. While I do like art I must say that in my perspective the story is much more important than the art. I would choose good story over good art any day which is why I'm not bothered when I read a book with terrible art but a good story.
To me it is easily a good story. Art and story work well together and may even help where one is lacking but story is more important. I can read a manga with terrible art as long as I am amazed by the story. In the end we tend to remember a story better than the art. Plus, a better artist can always be hired.
Considering a number of Manga are based off light novels, the story is important regardless of imagery. Harem series are fun and do actually have decent/good and funny stories to them. But if all you wanted was imagery to salivate over, you should just find yourself some fresh hentai. Don't need much of a story for that.