... at work recently. Bunch of crap the whole of them.
One basically only works reliably in Firefox, one only in IE, one only in Chrome. And then of course there is the problem that one other needs an option in Chrome set to "on", the other needs that same option set to "off" to work.
So at the moment it seems any more complex "web" application I look at basically needs it's on sandboxed browser to not interfere with all your other web applications, and the whole internet itself. And at that point, HTML is a pretty bad abstraction layer for GUIs compared to some of the desktop GUI frameworks.
The only technical plus side is that you "don't have to install anything on the client", but since we have Remote desktop server with "dumb" terminals anyway that is a moot point for us, we don't need to install anything on the client anyway.