The presentation is good but it had an opposite effect on me. It is not that I was and HTML fan before. But all of my fears have been confirmed - multiplatform nightmare (different browsers supporting different features), lack of tools, terrible language.
The only argument in favor of HTML 5 was that it almost caught up with SL in terms of its features. From my point of view, even if true, it is not enough - it has to catch up with SL in terms of the ease of team development and testing and I do not envision it happening any time soon.
I am also quite disappointed about not having the 3D API on Mac. Moreover, the way the MS built the 3D API making it dependent on XNA, it will probably never make it to Mac of if it does, it will probably be completely different between the two versions, so that the UI developers will have to build 3d applications twice - once for Windows and once for Mac.
Do not take me as a conspiracy theorist, but it seems that in order to promote HTML 5, MS decided to mess up the SL implementation.
I was actually appalled at the fact that MS is pushing this hodge-podge in place of Silverlight. Yes, there are now many things that can be done in HTML 5 that could not be done in HTML 4, but I still see no way to do build them fast and to facilitate re-use - something that SL's C# language and MVVM pattern allows you to do. Also - the proprietory CSS3 tags - just the old story all over again.