Not impressed. I was reading a review of these cards not to far back and noticed the 5750 had a power draw that was 75-80W. I'd much rather see a "green" version of that chip where its clocked down just a bit so you don't need the 6pin plug. It would then be the fastest card without one. The 5770 isn't much higher, they might be able to make one of those as well. That would be something.
You could just buy a 5670 and decide to overclock it when you want more performance instead.