John and colleagues define public-space quality as a layered structure rather than a single evaluative score. Their iconic contribution is a typology-sensitive framework in which accessibility, safety and comfort operate as foundational conditions, while parks, plazas, green spaces and public facilities require distinct secondary criteria. The theoretical advance lies in the proposed hierarchy: access enables encounter, safety permits use and comfort conditions duration and engagement. Methodologically, a systematic review of 159 studies identifies recurring and specialised factors across urban typologies, while also comparing subjective, objective and AI-assisted assessment practices. The conceptual operation is dimensional differentiation: comparability is preserved without dissolving local specificity into a universal index. The wider bridge reaches urban design theory, public-health research, computational assessment and democratic-space studies. The review also exposes a technological bias, since automated approaches favour easily quantifiable visual or physical attributes and frequently neglect cultural meaning, conflict, informal appropriation and political accessibility. Quality therefore emerges as both measurable condition and contested public relation.