It definitely isn't worth it if you're going to use a premade script. You shouldn't pay attention to people who say that DDL sites are dying either, the only reason why current DDL sites aren't that popular is because they're not that good themselves in the first place. I know I'd never go look for something on a site that links totally lame sites from their Index.

1. You need a good script.
2. Good domain.
3. A lot of traffic.

Webmasters will be emailing you 24/7 to get their sites listed if you offer good traffic, but that's about it. Traffic isn't worth it either if you accept lame sites.