Ha-Joon Chang is one of the most interesting economists out there, one who eschews mathematical formalism and takes a much more social history looks at the way economics operates. I was really delighted when the FT gave him a food column last summer - fantastic, diverting discussions about trade, war and development in the middle of a discussion of his favorite dishes. Always read him if you can!
It's covers all the major schools of thought, along with their pros and cons. I highly recommend it.