Do you think submitting to directories is effective?

If its a niche directory that has a good ranking for your keywords yes it should bring some traffic, if not no.

Submitting to authority directories like DMOZ will definitely benefit your site. Submitting to directories won't hurt your site as long as you submit it on clean and not on link farms directories. Somehow some SE's do still count directories as baclinks specially Yahoo.

i think yes because you are still link building or submitting a site. perhaps you should submit your site to those have PR submission sites..

Directories can help with anchor text and to rank certain key phrases and also provide backlinks. Directory submission is more beneficial for new sites that have no backlinks yet and pages that are trying to rank well for long tail keywords.
If you are looking for traffic from directories then stick to niche directories they may deliver some traffic because niche directories are considered more relevant then links from generaldirectories as these directories list only sites which are related to a specific category and are hence, considered relevant to the theme.

Submit site to high PR directories and niche directories is beneficial. there are lots of useless directories online, by which you will not get any result.

I thinks the submitting site in Quality and high Pr directories. then It's useful to Improve the SERP ranking.

Directories have proven an important source for links. These links should ideally be optimized for the keywords that we want our site ranked for in the search engines. Usually directories allow the submission of just one page (generally home page), so the keywords have to be relevant to that page. Make sure that you have researched your keywords well and chosen those that are minimally competed for but adequately searched.

HI
Yes,Submission to Good PR directory really help full to get good traffic and also Quality back link.

HI
Directory submission not improve good traffic but using Good PR directory submission help u to get good Quality back link and also improve your PR as well.