Tried deploying a simple Heroku echo app and put it through KeyCDN performance test... The fly.io instances actually perform worse in terms of TTFB compared to a single Heroku deployment in AMS.
Here are some stats. https://i.imgur.com/Qt1p29G.png
You're right user reviews on Amazon are manipulated. Bought a bluetooth earphone on Amazon DE, was contacted by vendor to exchange a five star for a half refund.
Also came across Facebook ads that asks you to buy random crap and leave positive review in exchange for a full refund, and they call this "free samplimg".