Get Amazon product reviews by ASIN or URL: review text, star rating, title, author, date, verified-purchase and Vine flags, helpful votes and variant, plus the product star-rating breakdown. Async: a first call with asin returns a snapshot id (collection ~40s); call again with that snapshot to fetch reviews. For review mining, sentiment, complaint detection and competitor weakness analysis. 亚马逊评论挖掘与差评分析。