Automatic submission has it merits. For one, it's quick and easy. But along with it comes a high risk of getting closed down by Google. I wouldn't go for it, if I were you.
I don't think it's a good idea as Google has recently said it willbe going after content farms, i.e. duplicate content, so good article directories that manually review each article to prevent duplicates like Ezinearticles are the way to go
Getting involved in automated submissions is taking a huge risk that is getting your website penalised or banned. I would go for manual submission which is safer and long-term when it comes to results. It's the better way to go if you have no plans of belonging to Google's banned list. The process may take longer, just like what the rest are saying, however, the result would be better and your site would benefit greatly.
Automatic submission is okay IMO as long as you don't submit it to 1,000+ directories that way. Around 100 can't do any harm and you will gain time. Anyway for major directories, it's necessary to do it manually.
I believe this poster has the right of it. Automatic is fine in many cases as long as you are given options as to which directories you are submitting to and that you are not intending to submit all of your articles at once. spread it out. Rewrite between waves. If automatic is going to be seen as organic you must emulate organic submission by doing it over time. However at the prices offered by some of these manual submission companies I would recommend the reasonably small investment in manual submission services.