1. As per my experience Zendesk is a very impressive, efficient and convenient web based help desk application.
2. It delivers elegant ticket management. It is easy to manage and has a self-service community platform.
3. Multiple features are available to configure and to use Zendesk like chat, Twitter, Facebook, performance meter.
4. Integration with business applications (like MS Dynamic, edocr, Drupal, BlackBerry etc) is possible.
Room for Improvement:
1. Agent module is clumsy.
2. Customer search is disconnected.
3. Many channel inquiries are not possible to collect into a single interface.
4. No URL integration with back office system.
5. Customizable help center is not available.