Without strong characters (and by strong I mean well thought out and developed characters), you won't have anyone for your readers to root for. Without a strong plot you have a meaningless story and characters without enough to do. A strong opening is a must to draw readers in, but a strong ending means the reader is likely to want to read more of your tales in the future.
Does your story have the impact on re-reading it (ideally many times) that you want it to have? Have you got rid of any of the dreaded boring bits? Is everything relevant and/or moving your story forwards? If the answer is yes, then get your story out there. It's definitely worth trying to get it published.