With 16 one star ratings given to the plugin over the past week, it might be worth taking notes from your users (many of us who were looking forward to a Pro version, but don't like the way it was introduced).
I've got absolutely no problem with paying for plugins and themes, but I've always felt that the way to encourage users to upgrade to PRO was to offer MORE features in the pro version - new features, better support, etc... Not to REMOVE the features from the free version, forcing people to upgrade to get the old functionality back. This (obviously) causes quite a lot of resentment, as you can see here (regardless of whether you think it's warranted).
When I purchase a premium theme or plugin, I do it because it offers me something more than the free version. Obviously, your Pro version now offers something more than the free version, but only because you have reduced the functionality of that version. I don't think I'm alone in thinking that this is the wrong way to encourage people to upgrade.
I know that when I click update on my plugins, I do so expecting that I'll be updating to a more stable version. I'm clearly not alone in this expectation, and I'm sure I'm also not the only one who doesn't check the blogs of every plugin I use every week. Most of us update our plugins from the WordPress dashboard - the changelog offers no indication that features will be removed as soon as we hit update.
I was looking forward to the Pro version, and recall reading this entry at the end of July: http://www.adrotateplugin.com/2012/07/adrotate-pro-coming-later-this-year/ where you detailed some of the improvements the Pro version would offer.
The new direction will be that there will be 2 versions of AdRotate. The regular version which you have now will remain available but also there will be a Pro version offering even more features and of course great support.
The free version will of course promote the Pro version but will remain a 100% functional plugin. However, fancy new features will be added to the Pro version and not the free version. A detailed list of which feature goes where and in what capacity will be made available when such a list is made and ready.
This sounds to me more like the right way to go about rolling out a Pro version.