From my perspective, Bloomaert provides a fantastic way to use his influence from complexity and chaos theory to understand and advance both ethnography and linguistic landscape as methodologies. However, the beginning of the book is (as expected) heavy on theory - if you're struggling with this part of the text, try skipping ahead to see his analysis and then coming back to read the theory again.
Perhaps the single most useful thing I took away from this (in terms of linguistic landscape specifically) is the historicity of signs: the way they point to the past as an influencer, the way they indicate simultaneous infeluences in the present, and how they may be used to understand future influences or expectations of people who read them. Another useful perspective was the inherent nature of change and complexity within a structure: structures may show stability at a larger level, or change may be incorporated as part of a consistent structure, but at some smaller scale there is always tension and changes that, over time, will lead to the overall "stable" structure shifting. This is useful not just in linguistic landscape and ethnography, but a helpful consideration in any social science study or project.