As long as you understand where he's coming from, and that he's been paid as a lawyer to advocate in the past for clients, his stuff is worth reading. His arguments may be biased towards a specific perspective, but they are well-reasoned and documented in support of his position. That's a lot better than the normal bovine effluent you read from tech reporters or (other...) paid shills.
Even PJ would pick-and-choose references to support a position, that's what "making an argument" is all about.
That being said, Mueller's recent writings on Apple abandoned a lot of the balance they had in years past. I don't know if he lost patience with Apple's positions on the Samsung trials, or if his change was motivated by something less transparent.