The bottom line
If you regularly buy from independent direct-to-consumer brands, Shop.app earns its spot on your home screen. The checkout speed, parcel tracking, and security architecture together represent a genuine improvement over typing your card into individual stores.
If you do most of your shopping at Amazon, Walmart, eBay, or large legacy retailers, the marketplace and Shop Pay layer are mostly redundant — but the universal tracking inbox alone may still be worth installing for.
Either way, the trade-off is worth understanding before you save your card. The strengths are real; the weaknesses are real too; and only you can decide which side outweighs the other in your particular shopping habits.