With Visual Studio 2010 the Visual Studio documentation viewer has been completely redesigned. And apparently it is unfinished. The final viewer won’t ship until later, maybe VS 2010 SP1.
The interim solution is fairly awful.
Help and documentation is viewable in a browser window. For local help a ‘Help Library Agent’ must be started first. The agent creates an HTTP service at 127.0.0.1:47873. Each time that the agent is started the host and port remain the same but the URL path contains an ID that is different. So local help can not be bookmarked. I can think of some interesting reasons for creating a local server for the local help but with what the local help currently provides I see no evidence that the local server is needed. It seems to serve no purpose, except that it breaks bookmarks.
For local help a full table of contents and index are missing. If you are accustomed to browsing the TOC or using the index, you will be frustrated.
You can get a full table of contents with the online help. With the online help click the Preferences link in the upper right corner and choose ‘Classic’. The Classic view provides a full table of contents.
For local help there are the following two tools: