I entered this stuff into our bug database. Thanks. The team is very active, already working on the next release. We're tackling performance and any other issues such as the ones you brought up. Anything in our control, we'll fix. The rest, I'm very confident, Microsoft will address in the next version of WPF.
As for wether WPF is ready for prime time, we'll see what developers come up with before the next WPF update and release of the Orcas tools.