As the first directly imaged planetary-mass companion, 2MASS 1207 b has been instrumental in shaping our understanding of exoplanets and brown dwarfs over the past 20 years. In this talk, I will review previous key findings and long-standing questions surrounding this remarkable world, and present new atmospheric characterization results based on JWST spectroscopy. Our analysis employs a newly developed atmospheric retrieval framework capable of modeling both homogeneous and inhomogeneous atmospheres, incorporating the effects of patchy clouds, hot spots, and their combinations. We find that the atmosphere of 2MASS 1207 b is best described by a patchy cloud scenario: 9% thin-cloud patches emitting L-dwarf-like spectra and 91% thick-cloud regions producing blackbody-like emission. These results provide a coherent explanation for the weak CO absorption at 4-5 um, absent CH4 absorption at 3.3um, and the observed photometric variability. Notably, the retrieved atmospheric properties show large scatter in less statistically favored models but converge to consistent values in the best-fit ones, highlighting the importance of exploring diverse model assumptions in retrievals to avoid biased interpretations. I will conclude by discussing the broader applicability of our characterization technique to current and planned HST and JWST observations, as well as the forthcoming spectroscopy of self-luminous exoplanets and brown dwarfs from ELT.