alt Hacker NewsIt has single-threaded semantics per element. Which is fine for anything that does completely independent computation for each element, but is quite annoying for everything else, requiring major algorithmic changes. And CPU SIMD is used for a lot of such things.
"Completely independent" except for anything that can be expressed using branches, queues, and locks. Which is everything. Again, are you sure you've tried CUDA? Past, like, the first tutorial?