I've been doing software development very successfully for closing on two decades. I've developed in 680x0 assembly, x86 assembly, C, C++, MFC, ATL, Java, .NET and on and on in the fat-client space. I've watched with interest and anticipation as various parties have brought out the Next Big Thing.
I am also a strong advocate of web apps and have been for a long time. Reality has proven out my position as, as has mentioned, the web won the presentation tier (clearly this has nothing at all to do with data processing or database or system programming or anything of the sort).
In any discussion on web apps they are always held against an illusory foe that is all capable and all perfect. Let's get specific however -- I love Rdio and love their web app. They came out with a new .NET client so I of course gave it a whirl.
Worse, slower interface. Constantly updating (in big monolithic chunks). Consuming hundreds of MBs of memory.
I'm not trying to criticize specifically Rdio, but I guarantee that initiative started with someone slamming the web and its crazy mishmash of standards, promising that they'd do something that would exploit the full power of the client. The result was something much worse, holding the single and only advantage of "not in a web browser" (for what that's worth?). Amazon has fielded various trials with various rich apps (they usually partner with Microsoft), but you've never seen them because they never have a compelling story, coming with enough detriments that it outweighs the benefits. My local library system used to have a whole nasty Java interfacing tool that was an absolutely abomination, with a horrendous rickety interface that seldom worked properly, was slow, and was a beast. They replaced it with a dramatically better web interface.
Those are all just anecdotes, but they're constant across the space. Yet every post pretends that the web is a weakling that has no merit and no advantages, completely missing why it has made all of these wins against endless competitors.