What is half of what you're expected to earn? Have you asked what range would be 'proper salary based on performance'? Are they doing things that you are interested in? Will you acquire new skills that will be useful in your career?

If you are considering this offer, can we assume that there are few offers at this moment? Depending on your situation/skills/experience, maybe it might be worth giving it a try. 3 months isn't a long time.