Honestly, what a buy.
Pros:
1. Installing the strap blocks is, well, child's play. You just put them on, and you're free to jam in 20 seconds.
2. Stability is just as good as with any sort of expensive strap locks.
3. Value for the price is indescribable.
4. No need to install any outside parts onto your guitar. Very cool.
5. Aesthetically pleasing,
I do not think that the product has any cons.
It's perfect value for the money, and I don't see myself buying strap locks anytime soon, considering how useless and overdone they seem compared to these strap blocks. A very well-designed product, one of my favourites out of all the guitar tools.
I cannot emphasize enough how much I love the simplicity and functionality. I would recommend it to any guitarist.