Hello,
Directories are good for improving the authority's area and give a result in initial projects. Choose the right category also produces some good results.
All the sites I get a SEO work, I do the registration in directories, think that each one is one more domain with a link to your site. The vast majority, the links are follow and to register the job is too small, you spend a few minutes and sign up for a lot of sites.
The results are not surprising, but is a support for the initial work of linkbuilding, I think it's worth, including investing in some. The advantage of directories is that the domains are usually strong and is very easy to gain links to your site: D