I'd recommend it if you're into serious copywriting business or purchasing.
1. It gives you 10 times better results
2. It allows you direct text test with 2000 words at one time.. Whereas free copyscape can check only 500 words with a fair result.. For that too, you'd need to paste the content on some site to have the test URL.
3. It has got some new batch features that can alert you for anyone who copies your website content. Some good thing.