Components utilizing ceramic bearings are often significantly more expensive than those with steel bearings. So is the upgrade worth it? Is it all hype? Can they really make me faster?
The short answer is yes, quality ceramic bearings do offer a performance increase. They roll smoother and with less friction creating less resistance. "Faster" is relevant though; they will not knock 10 minutes off your next Ironman but they may get you across the finish line seconds faster in your next time trial. Most manufacturers purport a 1-3% watt savings and that is significant if you are a competitive athlete. However the same watt savings can likely be gained by cleaning a dirty drive train. Make sure you address the most simple/easy solutions first such as worn or dirty components.
The quality of ceramic bearings matters significantly. They must be perfectly round as they are much harder than steel bearings. If they are even slightly out of round a ceramic bearing will eat into the bearing races actually accelerating wear. The watt savings and component longevity is highly depending on quality and a high quality bearing takes several days to make. Brands such as Ceramicspeed charge a premium for their products but they can back up their quality. If you come across a great deal on an off brand ceramics bearing upgrade it is most likely not worth the money.
What about integrating ceramic bearings throughout your bike? Cumulatively pulley wheels, bottom bracket, and wheel bearings offer greater watt savings than just pulley wheels alone, but again the cost is significant. You have to weight the value of a small watt savings. But for those that want a slight advantage in their next race, and are willing to pay for it, ceramic bearings will edge you closer to the finish line.