as tess replies, it depends on your lifestyle. If you're from Philippines, Bangladesh, Pakistan, India, Nepal or country with a low cost of living, that would be sufficient if you're single. But if you're from other places, I don't think it would be enough. As the others stated, the cost of living in Qatar is going up and still climbing as the years goes by.

Besides, Nepali's and Bangladesh's works for 600-1000QAR a month and they are surviving in Qatar for years. It's still up to you on how you're going to spend your money. As of Qatar's lifestyle, you might end up saving your money since you can't afford to spend it here, or if you do, at the end of the day, your pocket would be empty.

Hope this might give you a hint.