Default straps at the bottom of the controllers would constantly get wound up along their length, and unwinding them was a really awkward process.
Compared to that, putting these things on and taking them off is almost instant, while having them fall off accidentally is still impossible.

One small negative is that I could use my hands (e.g., type something on my PC while controllers are still on) with default straps, but I can't with these. Taking the new ones off is still slower than just typing with the old ones on, but that's arguably not a problem.

A real negative would be the skin irritation after playing beat saber for a couple of hours, which didn't happen with old straps - they only left temporary red marks for ~16 hours. But note that I have pretty sensitive skin for a man, and also irritation mainly occurred on the right hand, which I tend to move more precisely (and so more sharply).
I found a compromise in comfort by having the right strap relaxed to the point where it doesn't feel properly (tightly) attached, but still not enough to where I can make it fall off by just shaking my hand. Having it like this, especially because it's different from the left hand, is pretty awkward, and there is still some skin irritation, but I'm not going back to the old straps.

Highly recommended

I absolutely love these controller grips. Not only are they super comfortable but they are also very useful in games where I need to move quickly.

Absolutely brilliant quest 3 controller straps with a easy to use battery door system and a comfortable grippy silicone that allows me to play blade and sorcery without the worry of destroying my controller