It depends on what you want to make with it. If it's just an experimental project or you want to knit something simple that doesn't have to look perfect afterwards - then you can give it a try. A lot of people report that yarn from there tends to be thinner and uneven, so the thread thickness fluctuates. That makes knitting more tiring and the result just doesn't look as clean. Plus the yarn often smells weird (not necessarily unpleasant, but kind of chemical), though that usually goes away when you wash it.
The bigger problem is that the quality is really unpredictable. Sometimes the yarn lasts forever, sometimes it frays when you wash it or pills quickly. So you're basically becoming a guinea pig. If you're actually starting out with knitting or trying to improve, I'd really get yourself a few decent balls of yarn - it doesn't have to be expensive, but yarn from well-known brands or local shops is just way more fun. The stitches sit better, the color is even and you actually see your project making progress instead of getting frustrated.
But if you already have the balls: just trying them out doesn't cost anything. See how the thread feels when you knit, whether it tears, how the stitches look. Then you'll quickly figure out yourself whether it works for you or not.