I've been using this since Syndol was developing it and good to see that Xon has taken over maintaining things as the support is top notch. I manually approve all new members and this add-on has made keeping track of sign ups so much easier.
I got this addon for free when we purchased Bookmarks and Thread Bans during Syndol's addon sale and I must say it is extremely useful to have.
We run a semi large RP site but we don't get registerations every waking moment due to our niche. So it's really nice to be able to know when someone registers and to greet them to the site and make sure that they are a real person.
I recommend this addon and all of the other addons Syndol has made, they are extremely important to our setup on our site and I'm sure you could find a use for them :)!