I don’t know the authors personally and I don’t work for the publisher----I publish with Apress:-) but I have to say LINQ in Action is one of the best technical books I have read in recent years.
LINQ in conjunction with the language enhancements in C# 3.0 / VB.NET 9 are incredibly important in terms of writing less code, writing more readable code, as well as adopting a common method to perform queries. However, I still meet with many customers who have not investigated either topic. It is a dramatic break from current programming models and most developers are pretty busy:-)
In my humble opinion, every developer needs to be knowledgeable in LINQ. You can pick up a lot just by playing with the examples available here as well as reviewing the documentation, however, LINQ in Action provides excellent coverage in a very approachable manner. By necessity, LINQ in Action also covers the new features in C# 3.0 / VB.NET 9 like the following:
It presents the new language features in terms of how the features enable functionality within LINQ as well as how the new features can help development in general. Once the basics are covered, LINQ in Action moves on to explaining the various ways to use LINQ with objects, XML files, SQL databases, even text files. Most importantly, LINQ in Action provides great coverage on performance implications of the various ways to query with LINQ.
When investigating LINQ, be sure to install the samples and LINQ Query visualizers available at this link as well. Happy Reading!