Google Image Search has just gotten a much-needed refresh that looks great, works better than ever, and keeps Google competitive with Bing's image search. At the risk of sounding like a Google advertisement, this update is awesome. As a regular image search user, I have to say that every change the Google Image Search team just made is an improvement.
First, the new results page: it's denser with images than ever before, and you can view 1,000 images in one scrolling page before you have to jump to another one. The thumbnails in the results are larger than before, too, which gives you much better idea of what's worth clicking on. There are also new keyboard shortcuts (page up/page down) to make browsing faster.
When you do click on an image, you're no longer presented with an annoying frame at the top of your browser window. That frame was the worst thing about Google Image Search, and I am quite glad they removed it. Instead, the image appears, full size, in a lightbox above a greyed-out version of the page where it appears. If you want to view the whole page, just click outside the image.