Couple of years ago, directory submissions were a great way to boost search engine rankings. People started to use targeted keywords instead of company name to help them achieve better rankings. Nowadays link from most directories do not hold any weight. There are still a few good directories but the majority of directories are worthless.
If you have an aged site, then submitting to directories won’t help you. However for new sites, it is a good way to get an initial boost of backlinks. Of course they will not contribute at all towards ranking but at least you’ll be getting a few backlinks which will help with your PageRank (PR).
The problem with directory submission is that it is a tedious task. You absolutely need to outsource it and fortunately you can get like 1000 directory submissions for a cheap $10. Although people use software to automate the whole process, you will inevitably have to scan through the long list of emails to confirm your listing and that takes a lot of time but there’s nothing you can do about it (well except if you write a program that loops through your emails and visits the confirmation link).
The only benefit that directory submission can have for an aged website is that it will hide your important backlinks. People check competitors backlinks everyday and if your good links are obvious, then your competitor will try to get a backlink from the same website too. Therefore you need a way to hide your backlinks and directory submissions can do that for you.