Amazon product page contains a section called
Reviews that mention. The section lists the main things that users liked or dislike about the product. For example see
this page. How exactly does it work?
This can be done using topic modelling using LDA. But this approach has several drawback.
You need to choose number of topics upfront. But in amazon reviews number of topics vary for each product. Number of topics are not the same even for products that belong to same category.
You need to give friendly name to each topic. With so many products its unlikely that amazon does that.
What approach would be suitable to do this in completely unsupervised way, without the drawbacks mentioned above.