I used to use Subscribe to Comments Reloaded plugin, but it took off some of the main features of the plugin like the ability for the commenter to subscribe to only his replies. That's very important because people don't like getting e-mail's for other people's comment. And I had reader's who complained about it.
The development of Subscribe to Comments Reloaded is steady compared to this plugin. The support for this plugin is also incredible. I never had any issues unsolved within a day or two.
What's cool about this is that we can BCC the copy to administrator as well.
This plugin came as a life saver to me.
This is way better than Subscribe to Comments Reloaded and must install for every blog.