Conclusion

For a developer moving to the .NET Framework, learning a new language will surely take some time. Yet neither C# nor VB is all that different from other programming languages, so most developers won't have too much trouble learning these new tools. Learning to use the .NET Framework class library will probably take longer. Probably no developer will need to master the entire library, but everybody will need to learn some parts.

Understanding the .NET Framework class library will take time

The good news is that by providing a standard solution to many common problems, Microsoft has given us a large set of code that we'll never need to write again. While it will surely take some effort to master the relevant parts of this new technology, we should receive substantial benefits. And however you feel about it, the .NET Framework is a reality. If you want to write Windows-based software, your choice isn't whether to learn it, but when.

Every Windows developer will need to learn the .NET Framework