We use Kenexa's 2x Brassring as ATS in a global organisation. It allows our Hiring Managers to provide the data required by them, and start/be part of the recruitment process without requiring access to the system.
A Client Services Consultant is pretty much required to navigate between bugs and the global support center. A Workbench trained administrator is invaluable.
Once languages have been added to a requisition, it is not possible to remove them without rebuilding the req and sending it for approval again. Many defaults point to the system having been originally designed to for system users to only work within a single req language.
Reported issues seem to too frequently end up in a loop between the 1st and 2nd level of support, or returned as being fixed, when it isn't.
Too many bugs, especially following a release of a new functionality.
The system is designed for all users to access the system, even though it may be sold as data can be accessed via emails. Out of system approvals and notifications are disappointing.
Too many functionalities which would help usibility are only available to standard fields, which for the most part are unusable.
Product releases are normally too far between and lacking functionalities which one would expect in 2014.
The Internet Explorer version supported is always behind, by at least one version, if not two.