- the lack of domain specific libraries compared to CUDA, for instance. However, AMD has released stuff like http://developer.amd.com/libraries/appmathlibs/Pages/default.aspx. Anyway, we should have always in mind that OpenCL is younger than CUDA.
- questions about why use OpenCL in environments without GPUs were answered by people arguing about the unknown user space (where your app will run) and stuff like http://www.khronos.org/developers/library/2010_siggraph_bof_opencl/OpenCL-BOF-Intel-SIGGRAPH-Jul10.pdf that points the direction of applications implemented on Intel's SDK.
The group is open and some helpful and qualified helpful members are creating interesting discussions.