Dynamic URLs vs. Static URLs - The Best Practice for SEO is Still Clear by Randfish, Seomoz.org (Sep 23)

So - dynamic urls do still cause some problems - they get indexed but don’t rank well.

“So - bottom line - dynamic URLs don’t afford you the same opportunity for search engine rankings, usability or portability that rewritten, keyword-optimized URLs do. Just because one of the engines doesn’t have trouble crawling them doesn’t mean it’s any less critical to continue optimizing this element of a site’s structure.”

Read more from the source