Directory links are still links you get PR, traffic & help rising up the SERPS for your desired keyword if you use the right anchor text
It is worth. Depends on if you are paying for a link. If you are not paying then your time is well worth. If you are paying you need to look at the page PR (The page your link is going to be) not the site PR that is my $0.02 Thanks
There is an thread here very recent with quite the same information. I recommend you to do your semi-automat submission using the software in my signature.
I have submitted my site to free directories, and now it's in the first page of SERPs for very compentitive keyword. So I think it's worth to do.