I find it helps me find out if my SEO work is actually effective and helps me come up with ideas to continue to improve.
using webmaster tools you can check check all the data of your website and also check the back links. The main advantages is that you can see all of your website pages when they are indexed or crawled and what should have errors.
Please discuss and tell me what you think of using Google webmaster tools and do you think if there is any advantage at all.