Miguel de Icaza says "Avalon marks the end of the American Dream." He also compares it to J2EE -- apparently implying that it is overly complex and overarchitected.
While I wouldn't put it that way, I can't disagree. I left Microsoft almost two years ago and Avalon still hasn't shipped. A 5+ year ship cycle for a project can't be seen as anything but a sign that something is horribly wrong. When I was on Avalon we kept talking about building an API for the next 10 years. Apparently, when Avalon ships there will be 5 years left on that clock.
I take partial responsibility for this. When we were first starting Avalon, I was all about "Go big or go home" and "We should build something only Microsoft can build." In retrospect, the project and the company might have been better served by starting with a much smaller team, aiming lower to start and shipping 5 times over those 5 years. Version 1 might not have been that impressive, but relentless improvement would have built something better factored, simpler, and more in tune with what users actually need.
I named this blog "eightypercent" in honor of the 80% rule. It just so happens there there are lots of 80% rules to apply. In this case, a simpler system that only solved 80% of the problem would have been good enough and would have shipped multiple times already.
It looks like the WPF/E project is an effort to strip Avalon down to something much more approachable. Cross platform, no full CLR, lower memory footprint -- sounds a lot like Flash/Flex. I know some of the guys working on the project and I have high hopes that it will be something interesting. The only question, when will it ship?