How stable is WPF not in terms of stability of a WPF program, but in terms of the ‘stability’ of the API itself.
Let me explain:
Microsoft is notorious for changing its whole methodology around with new technology. Like with the move from silverlight 1 to silverlight 2. With WPF, I know that MS changed a bunch of stuff with the release of the .NET service pack. I don’t know how much they changed things around. So the bottom line is, in your opinion are they going to revamp the system again with the next release or do you think that it is stable enough now that they won’t change the bulk of the system. I hate to have to unlearn stuff with every release.
I hope that the question wasn’t too long winded.
MS do have a history of ‘fire and movement’ with regards to introducing new technology into their development stack, but they also have a strong history of maintaining support for the older stuff, and backwards-compatibility. WPF seems to be getting stuff added to it with each new release of the framework but the things you learn aren’t being superceded or invalidated.
The only breaking change I’ve seen in my own WPF applications with a new release of the framework was one recently in 3.5 SP1, and that was because we were unknowingly relying on a bug to get a certain behaviour from our code. We adjusted the XAML to be more correct and it started working fine.
So yeah, I think WPF is pretty ‘stable’ as a client-side development technology.