As you probably expect, your answer is "it depends." If by "good school" you mean a top ten business school, you will need to make up for your lower-than-top-ten-business-school GMAT by wowing them with stories of your work experience. There are students who get in top ten schools with 590 GMAT scores, so you need to prove to them why one of them should be you. On the other hand, there are lots of "good business schools" where your 590 would be more competitive and you might have an easier go getting in. Look to the second tier and find a school that fits with your desired learning style and academic cultural preferences. The easy answer is to apply to several schools across the spectrum of difficulty and see what you get. If you have the time and resources to do this, you will likely find a match. Hope this helps.