When I looked at OpenCl, my impression was it was simply a kind of bundle of functionality that happened to be shared by different GPUs (thin-layer of syntax on top of each manufacturers chip) whereas Cuda is a library that actually shields the programmer from the complexity of programming a GPU. I think AMD is working on an open-source system somewhat equivalent to Cuda which might be nice to see develop. But it seems like the OpenCl consortium is the kind of organization that could never care about the individual developer or meet their needs. I'd love if someone could prove me wrong.