Downgrading wasn't a quick process for me. It's easy at the beginning: Install the 2.0.7 code and run wp-admin/upgrade.php like you normally would. After that, however, I ran into some issues.
One: All links were orphaned. I had to create new link groups and make sure my links were moved into them. I didn't think this was a major problem.
Two: Pages disappeared. All of the pages moved over to posts, so I had to recreate all of my pages by hand to restore the permalinks and content. I didn't lose them, though; they just moved over to regular posts, so I had to hunt them down, copy and paste the content over, and delete the migrated posts.
I'm not sure what other problems might exist depending on how you've used WP in the past. Those were the two major issues I saw after downgrading, but your mileage may vary.