Well, for starters, the little stuff that an SD camera won’t notice (wrinkled skin, etc) stand out like they’re painted on with HD cameras. Plus, at least the first generation HD gear had issues with rapid movements. If you suddenly jerked the camera one way or another, the picture would get choppy. Now, even SD will do this to an extent, but it’s very irritating to see it in HD.
HD also likes rooms to be better lit. The CCD’s have a lot more pixels on them, which means a lot less light hits each pixel. The result is that in darker rooms, you need more gain, which distorts your image. No fun at all.
Plus in general, HD just requires a lot more precision to work with. When it comes to handheld operation, I’m "the human tripod" with my SD gear, as steady as they come. But with HD gear, I can see a lot more movement in the picture. I suppose the biggest problem with a more accurate image is that it’s more accurate.
Hope that helps.
