Since 6.0, HTL should be used to develop components. HTL and SlingModels provide better facilities for achieving the same functionality provided in ComponentHelper, thus it is deprecated.
Purpose
Provide a simple abstraction for creating CQ-specific markup that drive component-based authoring elements like drop-targets and placeholder icons.
Example
The most common use case of the ComponentHelper is to control the execution of a component JSP based on it configured status.