If we talk about the quality web directory then yes DMOZ is one of the best example. Google trust the directory and use the data of dmoz in their directory. So if a website is approved in this directory atleast 2 excellent backlinks your website will get, first from dmoz and second from google. There are also hundred of web directories using ODP data. So follow the guidelines of dmoz.
DMOZ has page rank of 9 and if you are listed in this directory, google knows your website is genuine and consider that website is important.
Try to list in Dmoz
It would be very helpful but don`t expect that alone to shoot you up on the rankings. Also, I am not even sure if DMOZ is still adding new listings to their site.
Anyway, try for it but it is that important if it fails.
Dmoz is the best open directory. If you get listed in this directory than many search engines like yahoo , google , bing , lycos , altavista and many more will will indexed you faster .Also it will give you quality backlink for better serp.
