It's been discussed to death in the past.
https://news.ycombinator.com/item?id=22422873
https://news.ycombinator.com/item?id=28004515
https://news.ycombinator.com/item?id=18084013
https://news.ycombinator.com/item?id=26422286
https://news.ycombinator.com/item?id=25332101
From reading the previous threads, large projects are where it (apparently) really shines. Personally I didn't find it useful at all, but obviously YMMV.