Wen's book is a truly fantastic book, but I don't think it can be considered a "Solid State" text. It is a many-body book in the spirit of Altland and Simon, AGD or Fetter and Walecka. It is emphatically NOT in the spirit of Kittel or A&M. That's a good thing! But I think to really get much out of a book like Wen, it's BEST to have a traditional background in Solid State Physics.
Edit: Maybe I'm old fashioned (or maybe it's because I'm in a group which is actually well grounded by experiment), but I think to do condensed matter theory, you must have a rock solid intuition about classical band structure theory, the semiclassical theory of phonons, elementary treatments of magnetism, and crystal structures that you can't find in these fancy many body books. Wen's treatise is an aesthetic masterpiece, but to begin studying CMT there would be worse than suggesting one immediately starts learning E&M from Landau's Classical Theory of Fields (Or Jackson), rather than starting with Purcell or Griffiths.