Does pu-erh really get better with age?

It's real for sheng (raw) pu-erh, but only if (a) the starting leaf was good and (b) storage was correct. Young sheng is bracing and astringent; over decades, microbial fermentation transforms it into something rich, sweet, with notes of camphor, dried fruit, antique wood, and a thick body. Poorly-stored or low-grade sheng just gets older without getting better. Shou (ripe) pu-erh is pre-aged and improves only slightly over 10–20 years — most peaks at 5–10.