Low quality directories are frowned up with Google and SEO. Nonetheless, though, high-quality directories are O.K. with Google. However, I'm not sure how much a boost you get. Maybe it's just like getting a high SEO metric backlink.
That's a case for webmasters to dig deep to find the right directories to promote their site traffic through search engines like Google, Bing, Yahoo etc. Such will enable them cut down unnecessary expenses, and not just investing in any directories they saw online.
In the past, Directories (articles and web directories) were good place to build backlinks for your site and these backlinks actually worked. But these search engines consider these directories link farm, so directory for SEO does not work.