Authority work has been one of my long-time pet projects. Authority records, properly linked to headings in bibliographic records, make it much, much easier to globally update headings as changes occur. Authority records can help keep headings in bibliographic records consistent, and consistent headings allow users to search those headings in the catalog and get what they're looking for. Even if users don't know a thing about name and subject headings and just use keyword searches, hyperlinked consistent headings allow users to click on the headings and retrieve everything else that has that same heading (depending on system settings - and, actually, I'm not quite sure what our setting are like). It's very important that the headings are consistent, because, if they aren't, clicking on the link isn't necessarily going to bring everything up. The OPAC doesn't know that the hyperlink "Tiger" and the previous authorized form "Tigers" should be considered the same thing.
There's one thing about authorities that bothers me, though. When I was in library school, one of the touted benefits of using authority records was their cross-references. If a user doesn't know that the authorized form used by their library happens to be "Airships" and not "Blimps," the cross-references are supposed to help them find the records they're looking for anyway. The problem is that this assumes that users are doing browse searches. Anecdotal evidence (and quite possibly actual studies, which I haven't tried looking up) says that this isn't true. Instead, users, including a lot of librarians, are probably using keyword searches. True, they may be subject keyword or author keyword searches, but they're still keyword searches and, as far as I know, there is no ILS out there that searches cross-references in authority records in addition to text within bibliographic records. I had heard that SirsiDynix Symphony does somewhat, but, from what I can tell, "somewhat" means that, if the keyword search retrieves nothing, users are redirected to a browse search for that word. That can work well enough in some cases. If users don't automatically assume that the redirection is a completely failed search and actually click on the cross-reference hyperlink. And only if the keyword search retrieves absolutely nothing.
It would be nice if the cross-references of any authority record to which headings in a bibliographic record are linked were searched in subject/author/genre keyword searches (maybe even general keyword searches). If an ILS exists that can do this, I'd love to hear about it. And I'd like to know why more don't.