This cable is great for your old Nintendo DSi whose charger broke because of a frayed wire. It also allows you to use it with USB chargers, which are ubiquitous at free charging stations, or with your power banks or computers, essentially making them into extensions of the battery in the console.
The only thing I dislike about it (but not enough to remove a star) is that its cable and internal wiring are just as thin as the ones in the Nintendo charger, so it could break at the connection point if bent too much. I would love to see a version of this that’s a pure adapter from USB Type A or C to Nintendo DSi, that you can plug into USB cables to make them into DSi charging cables; that would give it maximum robustness.
Thin wiring is not too bad for the power transfer itself though, since only 2.9 W at 5 V is going to flow through this cable.