JD is keeping a tab of what the blogosphere has to say about Microsoft's Expression Suite launch.
I played around a bit with the Community Technology Preview of the expression suite which I'd downloaded a few months ago and used it to create a few designs. The Graphic Designer module was interesting while the Web Designer module seemed very similar to Dreamweaver and quite good. But the interactive designer/blend/sparkle was the odd boy of the lot. It borrowed a lot from Flash, but you had to do things differently to get it working. And although I have been using Flash for over 10 years, using MS Blend/Sparkle/ID was not quite straight forward as Mano would make you believe in his presentations. As a result I never got around the learning curve, and since my job as an interaction designer is not tied to the tool, I don't think I would really invest much time in it. At least, not now.
If there is a following in the future, it would possibly go up the same curve that Flash did in its early days, but maybe a bit slower as there is not that much of a 'disruptiveness' associated with the product.
Interestingly of the three, Blend is the only product that was designed and developed in-house, the other two were acquired. One more observation I had about the Expression Suite (at least the CTP) was that it did not gel together as one suite of applications, but more like a hotch-potch.
I'm sure things will improve in the future, and it is always good to have more than one option when it comes to tools to work with...