In Bruce Perry's article, Prototype: Easing AJAX's Pain, you can get a feel for prototype's shorthand notation, designed to minimize typing. For example, you can say $("mydiv") with Prototype as a shortcut for, document.getElementById("mydiv"). Bruce Perry suggests:

That sort of concision alone is probably worth the cost of setting up Prototype.

Well, that depends. Prototype is one of many available libraries for AJAX development, each of which has pros and cons, its own particular design center. A good overview of the various libraries is Survey of AJAX/JavaScript Libraries from the Open Source Applications Foundation.

If you have used any of these libraries, and have experiences to share that you think might help others figure out which one to use in what situations, please reply in this forum. What libraries did you try? Which one did you decide on—and which ones did you decide against—and why?