This is an excellent book, so I'm surprised it's only been mentioned once before in the science book forum. It deserves a lot more attention than that, so I thought I'd at least post a recommendation. The full title is "Lectures on quantum theory: mathematical and structural foundations". If you have already taken a QM class and want to understand the foundations better, this is a very good place to start. This is supposed to be a fairly easy book, so he has chosen not to include the difficult mathematics (advanced functional analysis, how to find irreducible representations of symmetry groups, etc.). But he always lets you know what he's leaving out, so that you know what to look for if you want to know more. It's written for undergraduates, but I'm sure a lot of graduate students would find it useful too. It contains a very good discussion about state preparation and measurements, and about some of the interpretational issues. He doesn't go into detail about the various attempts to interpret state vectors as representing objective properties of physical systems, but he talks a lot about "realism" vs "anti-realism". The book also contains an introduction to quantum logic at the end. It contains a small number of exercises, with complete solutions.