This is my second set of Shimano's metal disc pads, which have excellent stopping power for the price. They installed in minutes on my Cannondale CAAD 12 disc, putting the stopping power back in my Shimano hydraulic brakes. As noted in the title of the review, they tend to be louder than resin pads. If you're not bothered by the noise (I'm not), and want to stop efficiently, go with these. I reduced my rating from 5 to 4 stars simply because for some they might be too noisy for some riders. I definitely recommend.
I was nervous about changing my hydraulic disc pads myself, but actually its really easy. Check out a Park Tool video on changing these pads-it will take you about 10 minutes.
These pads work well and are easy to install. There was no need for a break-in period and they are quiet. They were the same as the original brake pads that came on the bike and lasted about 7800 miles.
I prefer the metal compound pads for most situations. They have faster initial bite and overall better stopping performance in wet and dry conditions. They also last longer than the organic compound pads. The only situation where I dont like them is riding in a race peloton. Shimanos Servo Wave Technology causes the braking to be a little touchy with these pads and its harder to make subtle changes in speed.