I am not enough of a mountain biker to be able to compare these cleats to anything else but my experience with them has been totally great. They never seem to wear out. Very easy to install. SPD cleats don't hold onto mud or other grime. I would recommend cleaning them off of course and checking to see the haven't loosened every so often.
I'm in agreement with Mary who also reviewed these cleats. the silver ones have way too much float so it takes an extra extended effort to get out you're moving around and them without actually releasing. I much prefer the black cleats that usually are what comes with pedals when you buy them new. Generally speaking if you've been using the black cleat and you switch to these you'll make a motion to release and you'll move but you won't come out so if you're looking for a certain amount of precision don't buy these.
I am going to post my insights on these clipless shoes and my peddles from a newbies perspective. Yeah, I don't get the clipless either, as I clip into the peddles... I ride about 20 miles 2-3 times a week, using a 29er mountain bike with slicks. I was scared to death of clipless, because I thought I would not be able to get out of them. I ordered the Shimano SM-SH56 SPD cleats to go with Shimano PD-M530 SPD Clipless Trail Pedals and Giro Rumble VR MTB Shoes. First off on the shoes, there is a channel that allows you to adjust the cleat position fore and aft, which helped me find the best fit. The Shoes are a bit heavy, but very solid and fit my feet well. The one thing I want to pass on, is the SM SH56 Cleats are multi release, so you can release your foot by twisting left or right. Plus you ARE NOT locked in to the peddles. You actually have some play where I can move my heal left or right by 12 inch to 34 of an inch. Which is really cool, as sometimes I have a little pain in my knee and by moving my right heel laterally I can take the pressure off. It really did not take me long to get used to clipping in and clipping out of the clipless cleats. You can adjust the tension on the peddles for the release pressure, and I have mine set light, but they don't come out on the upstroke. If you are considering trying clipless, go with the SM SH56 cleat, and these shoes, they were a good purchase for me. I was able to increase my pace on my circuit by 12 to 34 of a mile average. I went from 14.6 mph avg. to 15.1 and have gone faster but that was on a day when I had a good south wind. Overall I am very happy with this set up and would encourage anyone looking at trying out clipless to clip into their peddles to try this combo.
These cleats are used in place of the standard SPD cleats, and allow you to twist your foot out of the pedal in any direction, including a hard yank straight up. This means, when your bike is going down you can literally leap out of the pedals and land on your feet rather than being pulled over with the bike. For many mountain bikers it is a good compromise between clip-in pedals and flat pedals, and is also great for road or cyclocross. These have several times saved me from more serious injuries.
I like to ride clipped in, but since the majority of my riding is commuting in a city with plenty of stoplights, I appreciate the ease of clipping in and out with the multiple release design. I typically clip out in a manner that would work with normal cleats, but the multiple release has saved me from taking a dive in a couple emergency stop situations.
Shimano SM-SH56 SPD Replacement Cleats are the best for beginners. You can adjust them to disengage at different tensions. Help in keeping a better cadence while riding. Easy to install replacement cleats. I would highly recommend.
In the interest of being helpful, I'll provide candid feedback on these cleats.
To be honest, didn't like these at all, because was used to the black ones that were more secure. I was popping out of them right and left, even after tightening them. I ended up taking them off and buying a pair of the black ones to replace them.
Hope that's helpful. Sorry it's not more positive feedback.
I must have gotten a defective one because my shoe came off the pedal 5 times (!!) in 30 miles, and if I hadn't been alert and quickly raised my foot, and let it fall and drag on the pavement, I could have broken my foot, my leg, or worse. It could have been a disaster.