Is there such a thing as OverAJAXification?
From the AJAX Sucks Department...
Jeesh. Everybody and their brother is sticking AJAX into their "stuff" - whether it's appropriate or not. They just did it at Codeplex.com. The search facility was just fine. You'd click a "next" link and the page would postback and right away you would get to see the next page of results.
Now, since they've supposedly "souped it up" with AJAX, what you get is a very long (sometimes 5 seconds or more) grey screen with an "updating" in-your-face graphic to look at, and then finally you get to see your next page of search results. To me, that's a lot more annoying and disruptive to the user experience than the slight flicker of a quick postback. But often, instead, you may just as well see the above Sys.WebForms.PageRequestManager exception dialog, which does absolutely NOTHING to improve the user experience.
Oh, and while I'm ranting, here's another nasty side effect of your "OverAjaxification": I put in a search term, and page through my results, and I'm on page 7, and I click "back" to go back to page 6, right? NOPE. You guys put me back on page 1! What if I click on a result to look at the project, and then click back to get back to my page of results? Same thing - you guys are now putting me back to the first page of results, without the sort that I chose. DOH! This is like Dan Rather and the Selectrics, man! Do you have to do this dumb stuff?
This is what happens when people are hot to showcase some technology but they don't THINK first. AJAX (excuse me - Remote Scripting), like any other technology, should be used with care and especially with great forethought as to its appropriateness within the specific presentation paradigm and web traffic load.
AJAX can definitely improve the user experience when used with care and in the right situation. But frankly, if it's going to bomb out or take longer for me to see my results than a simple postback, I'll vote for the old fashioned way every time.
The key thing is "form over substance"- we should always favor doing things in a usable, correct manner over "how they look". IF you can do both, then fine -- but make it stand up to the test first.