I just replaced my own My Two Cents comment system with DISQUS. The reason is simple: spam. Over the last months comment spam increased so much that it became a pain to manually clean it every time. I'm not sure if someone bothered to break my CAPTCHA or this was all cheap manual spam. I guess the latter.
DISQUS should hopefully be better at automatically recognizing spam and is also easier to moderate for me. It also has a few advantages:
There are also some disadvantages:
I'm looking forward to your (non-spam) comments