I am not sure exactly how one is expected to review a reference volume of over eight thousand pages (actually the true total is nearer 12000 because despite what it says on the covers there is a fifth volume - in parts A and B that is not included in this set.) but here is some information that may help potential purchasers (not readers because even those who enjoy reading dictionaries will not want to read these)
First, the trivial information that the four volumes together will exceed the carry on baggage allowance for most airlines and keep you exercised. Joking apart, these are heavy books.
The books take each element of the .NET Framework Class Library and documents it with the following:
A brief statement of what it does followed by a summary of its 'provision' in Visual Basic, C#, C++ and Jscript. Each function has documentation on its parameters and return value as well as any possible exceptions. There follows a brief set of remarks followed by a set of requirements. These are the platforms on which the function will run.
Around ten per cent of the entries include brief sample code.
Very few entries are longer than a page, while less than half a page seems more normal.
I have been very critical of the sheer size of the Java libraries. Their size makes it unlikely that they are uniformly high quality products. It is also hard for a user to have a good overview of what is available. However this framework library is more than twice the size. It is not my job as a book reviewer to comment on the quality of the product being documented but, as a programmer, it leaves me despondent.
If you are going to do serious programming for .NET you need adequate documentation and you will need to choose between books such as these and the electronic equivalent. Alternatively you can rely on 'wizards' to do most of the work for you. However when such generate code fails to meet requirements you will need to refer to the documentation to discover exactly what the generated code does.
I do not think recommendations are relevant here. If you .NET documentation in hard copy you need it. If you do not you won't want these books cluttering your reference shelves.
Next time someone tells you how complicated the STL is, remember that you only need a few hundred pages to document it. A few months practice will allow you to master it. This won't be true for the .NET Framework libraries.