It was a bit hard to install, but that's not the brake block's fault, it's just how it is. It is incredibly powerful, it stops your bike in like a second, almost in an instant and of course you can adjust it so you don't stop instantly because that would be dangerous. I would highly recommend this, the shipping was fast although I chose expedited and it came 2 days after I ordered it. Good stuff.
I think they're great. They lose performance under rain though, but it might be because my old bike has weak plastic levers (they bend and are not really responsive) and the rims braking surface have been used quite much.