Joost de Valk has an interesting post today on why it’s a bad idea to auto-generate meta-descriptions for your blog posts:
The reason I hate this “auto generation” idea so much, especially for content sites, is that it makes people think that SEO is something you can do on auto-pilot. You simply can not. While a good SEO plugin can help you take care of the technical boundaries that might exist, creating link worthy content is the process that will help you get rankings, all the time. Auto generating a meta description has never served any purpose to anyone just yet.
His opinion on the topic matters – he’s the guy who created the WordPress SEO plugin that I use on all my sites and recommend to my clients.