The 6.x-2.0 version of the ad module introduces channels, weighting, and premier advertisements, offering much greater control over which advertisements appear on your website, where they appear, and how often they appear. The ability to display advertisements on remote websites has also seen several improvements. The ad module's reporting layer has received many enhancements, among other things allowing advertisers to run reports over specific date ranges, and giving administrators the ability to export statistics as CSV files. The underlying caching layer has been completely rewritten, simplifying the underlying code to minimize bugs, facilitating integration with third party code, and improving overall performance.
The entire code base has been reviewed to ensure E_ALL compliance, ensuring general correctness, and improving security. Thanks to the active participation of dozens of beta testers, there have been countless bugs fixed during the active development phase.
Finally, the ad module's permissions system has been greatly improved. All standard Drupal content-type permissions have been properly implemented, and the ad module's own permissions layer has been moved into an optional module and further enhanced. The ability to define different advertiser roles and to control exactly what each of these roles can do has been greatly improved.