It's certainly doable, but I suppose the opinion of good or bad depends on the kinds of features or functionality you want to get out of the Gatekeeper.
Here's an old presentation, but perhaps still somewhat useful:
http://www.vide.net/conferences/spr2002 ... /kirby.ppt
If you dig around looking for documentation on the GK, you might also find documentation on the "MCM Proxy". I believe that functionality is still in the Cisco IOS Gatekeeper, but I do not believe it is supported any longer. Regardless, there is a newer product that replaced that called the Cisco Unified Border Element (CUBE). As the name suggests, it is a border element that can be used to route call signaling and media.
As shown in the presentation, the Gatekeepers are designed to resolve addressed across the entire network by sending LRQ messages (as defined in H.225.0) to other Gatekeepers. This is all done through static provisioning, but it's highly scalable and designed for carriers -- and it's used by a number of carriers. Nice thing is the functionality is available in smaller enterprise class routers.
The Cisco Gatekeeper has the ability to register terminals, but its strength is in managing Gateways, ensuring that the proper gateway is selected, calls are load balanced across a set of Gateways, etc. It lacks the ability to use H.323 URLs, for example, as a part of address resolution. That said, I'm not sure if an commercial devices use H.323 URLs, anyway. (I know some of the open source products do, but commercial products tend to stick with phone numbers.)
I hope that help.