I disagree. Shiny is very very nice, so long as it works.
Drop down (DHTML) menus are extremely common now days, and from a professional standpoint, very useful. As for "compatibility" for those morons still running shit like Netscape 5, IE 4, text browsers, etc... well they can just get bent. It's 2007, time to upgrade. Heck MS won't even push new updates to your windows system in anything under IE 6 anymore, so that should hardly be an issue.
So, shiny is totally, completely, 100% safe to use. Just make sure to test it with older browsers if you can, and if at all possible, avoid writing your own JS for it, use an existing lib with a nice small footprint. I'd suggest jQuery and some of it's addon's for something like this.
Web design is all about the look now days. Especially when you have a product you want people to know about.
There's my $0.02.