RonFrank
Contributor
IMHO, high ISO is great everywhere.
I've never been a *High ISO* man with the exception of TMAX 3200, but that was back in the day. But way cool grain, and great for concerts, artsy stills, or even some landscapes. I've also seen some very cool images out of UW SLR's using TMAX.
My goal is generally to shoot at as low as ISO as possible. I find digital grain... NOISE... not very acceptable. This does depend a lot on what you do with the final image. ISO 800 is fine for 8x10's or web. If you print a shot large, even ISO 400 has very noticeable noise. If anyone doubts this, take a look at DPReview. Phil does a very nice job of showing 100% crops side by side from low to high. Even one stop beyond the lowest ISO is noticeable no matter what DSLR one is using.
In a PnS, generally shooting anything but the lowest ISO results in noticeable noise. This is why a larger sensor is SOO much better.