Workflow is amazing
Designers and programmers can collaboratively work on files at the same time using XAML. This could change the way we work. No more hand offs of cut files and style guides so developers can get working. No more waterfall schedules. This could be game changing.
Potentially easier to sell to IT groups versus Flash for RIAs.
The entire process can be put into source control systems
Since it spits out XAML, the files can be source controlled, unlike FLAs.
No Mac based design tools
The Expression Suite is PC based. Sorry guys, asking designers to adopt a new tool and platform is too much to swallow even if there are benefits. Not a great way to endear yourself to the design community making them change for you. I have 3 copies of Expression here and I can’t even test them without a lot of effort.
Requires a plug in.
Low numbers for adoption of the plug in. Microsoft is unwilling to put it in Windows Update (understandable). So it will need to spread based on user demand. I predict 80% adoption in 2 years.
There is more to Silverlight than I won’t go into.
Overall, I was impressed. But a lot needs to happen before we could work with it.