I don't mind it if it's snappy and the image loads almost instantaneously, which is what I got when viewing this demo. Typically, with javascript, I'd have to wait a few seconds for the loading-wheel to spin until the image finally loads. Not that I can't wait a few seconds; it's just annoying.
Worse is when there's a series of images being displayed in a lightbox and because the whole thing "needs" to be centered and the navigation is not absolutely positioned, the next and previous buttons move around on the screen.
Yeah, I forgot about that one, which is by far the most annoying. Often times I have to scroll down a page just to get to the nav buttons. Down with lightbox!
These are all criticisms of bad implementations of lightboxes. Used correctly, they can be quite useful. The trick is to realize that you're interrupting whatever other workflow the user is considering on this site.
For example, a lightbox that fades when you scroll the page might be less invasive.
But the initial page load takes longer because it loads the full size images along with the thumbnails. That could be a deal breaker with a large set of images.
Given the limited amount of data that can be displayed on a screen at one time, you should never have to wait. If the loading-wheel is spinning long enough to see, I consider that a bug. Yet a stuck loading wheel is pretty much synonymous with ajax. I see it literally everwhere I go. What gives?
