There's AMD's CodeXL: http://developer.amd.com/tools-and-sdks/opencl-zone/opencl-tools-sdks/codexl/
CodeXL is a successor to gDEBugger and offers pretty much the same functionality with small updates. CodeXL works also on NVIDIA GPUs, but you cannot debug shaders etc.
Viewing buffer and texture contents works OK. It however does not support direct state access calls, which is a pain in the ass.
The second option is NVIDIA NSight. AFAIK it works only on NVIDIA GPUs (I don't have an AMD to test it), but works really great.
Both support Visual Studio integration and both really help debugging. I myself consider NSight more mature and somewhat easier to work with.
There was a nice video about Nsight, I think this is it: