Dense but very rich; it presumes no prior acquaintance with graph theory or spatial stochastic processes, but a very good grasp on measure-theoretic probability, and a lot of mathematical maturity. The first few chapters build up gradually from an opener on electrical circuits (!) to random spanning trees, self-avoiding random walks, "influence" theorems and phase transitions, percolation theory, and random cluster models.
His monthly "Books to Read While the Algae Grow in Your Fur" post for August 2015 — the books he read that month and feels he can recommend.
bactra.org ↗·2015-08-31