It's the second (that I know of) such free third-party notification system for HN to go defunct. If everyone whines about it enough, maybe someone will do a another one. ;)

So thank you for posting your question. :)

Edit; It occurs to me, you shouldn't have gotten a notification for my comment because I didn't reply to you. The previous service posted notifications of comments on your posts, plus replies to your comments. This one only notifies you of direct replies to your actual comments, not comments on your post.

So that's not necessarily meaningful data that you don't have a notification of my comment above. Did you get one for this comment?

sadly I'm on mozillium, but I'll upvote for effort :P