I'm not so impressed with MSDN. It's massively redundant and poorly organized, and they require you to install IE 4 to use it (as of July 2000; no doubt the required version will change over time, since it used to require IE 3).
Everything is just thrown in there, with very little structure. The only practical way to find anything is to search the whole library, which means wading through a lot of irrelevant garbage. By default, the Windows CE documentation comes up first in most cases. That's bad, because Windows CE is different in a lot of ways. This is really annoying. You can filter that out, in a crude way, but it's not convenient. With each new version, they make it increasingly difficult to get to the plain Win32 C API information. They'd much rather tell you about MFC. Of course, the MFC documentation is somewhat flakier than the Win32 C API stuff, and when doing MFC I often need to look at the Win32 C API equivalent to figure out what's going on. The MFC documentation is bad. If MFC weren't shipped with the source code, it'd be unusable.
They mix Visual Basic and Office documentation in with the real documentation, and the whole thing is leavened with useless "user guide" fluff ("To open the file menu, click on the file menu in the menu bar") for various IDE's, Access, etc.
Lately they seem to have stopped including portability information for C standard library functions: They used to have a little table for each one, with checkmarks indicating ANSI, UNIX, etc. The last time I needed to know, I looked and it was gone.
They also keep changing the file format and the viewer program. With each change they remove more functionality.
The only good thing I've noticed with it recently is that the Win32 C API pages have finally, this year (2000), been re-done.
As technical documentation goes, it's better than average -- but it's still lousy.