As with many things in business and in life - you usually get what you pay for.
There are always exceptions to the rule, but online, most free offers are not what they appear. Whether it’s that free Wordpress template you downloaded or the incredibly large and free gmail account you have, you are paying for them in one way or another. The same is true with a free web directory.

Unlike with a
free article directory, which accepts free article submissions and posts them within days, free web directories often take many months to review your URL submission. Submitting your website to free web directories is an exercise in patience. Your site may get accepted into some of them, but it will often take six months or more, since you are not paying a submission fee.

In contrast, a premium paid web directory will review your site within a week, sometimes within a few days. These paid web directories are not filled with spam and MFA (made-for-Adsense) sites and are almost always reviewed by a human editor. There is a greater emphasis on the quality of the listings in the directory. Although approval of your submission is not guaranteed, your submission fee is refunded if your link is rejected.

Since you must pay to submit to a premium paid directory, the directory itself must have high value (measured by Google Toolbar PageRank). To get a higher PageRank the directory owner must promote the directory extensively and often spend thousands of dollars and a lot of time to establish his/her web directory. The higher PR of the directory pages confers higher PR to the outgoing links on the page. So it is possible for your site to get a PR3 from one PR5 backlink in a directory. But most free directories (with the exception of DMOZ) have inner pages with a PageRank less than four, so these listings are less valuable.

It doesn’t hurt to submit to free directories. You aren’t spending any money and some of your links may be approved, but if you are serious about establishing your site in a timely manner, there is little else that can increase your PageRank better and faster than submission to premium paid directories.