Digital systems design with VHDL is a great book from the VHDL perspective. As the other reviewer said, it's presented in a hardware perspective rather than language features, but I would say that some chapters tend to be language features oriented.
It must be said that this is the only book I've seen that takes the time to explain testbenches, simulation and other subjects that, for better or worse, are very important for the complete design of a digital system from a "programming language" perspective. It does that by implementing complete or partial chapters wich concentrates in explaining this kind of stuff and in an organised and easy to follow way.
Now, this book could be more than awesome depending on what you're expecting from it...:
If what you want is a book that delivers in depth hardware concepts at the time that delivers VHDL code, language features, etc... then you should keep looking because, even thought it does give concepts (the chapters are presented in a hardware perspective), they tend to lack depth. The book concentrates explaining VHDL code for those hardware entities at the time that introduces and explain the language features and concepts needed to create and/or elaborate something.
If what you're looking for is exactly what I just described: a book that, even thought doesn't gives to much explanation about how hardware physically works (it does exist thought), delivers example codes and language features in a way that tends to be easy (and not because of that vague), explaining portions of code for a better understanding of what's happenning and implementing the language features VHDL works with (syntax and all other stuff), then this is the book for you.