The page where a shopper decides to buy or leave: your single most important piece of conversion real estate. Most paid traffic lands here, not on your homepage, so a weak PDP wastes the ad spend that delivered the visit. The job of the PDP is to answer every objection, show the product in use, and make the next step obvious.
Benchmark. Judge a PDP by its add-to-cart and conversion rate versus your other pages, and remember most visits are mobile, so design the mobile PDP first.