When the road bike had about 16,000 miles on it, the shifting started becoming erratic. The chain would jump between gears on the rear cassette, and cleaning and carefully adjusting the rear deraileur didn't help. I replaced the cassette, the chain (which only had about 4000 miles on it), and the shifter cable, all at the same time. Now the shifting works fine, but I'll never know if it was the cassette, the chain, or the cable that fixed the problem. The cassette is well made and easy to install if you have the right cassette tool and chain whip, otherwise it would be very challenging. The next time I encounter shifting problems, I'll start by just replacing the cable before replacing the more expensive parts.
I find Ultegra cassettes bullet proof and a good value for my training bike. They are relatively inexpensive and last a long time if you take care of them. Highly recommended.
Finally gearing that is intermediate between Mountain and race. The 12-30 10 speed is perfect on my cross bike for some serious off road and touring rides. Shimano quality is also a big plus - quick shifting and durability is a given. I bought the cassette for a loaded tour and now use it to take on local MTB trails. It has made the cross bike more versatile and fun. I would recommended for adventure rides, steep road climbs and tours!
I am still running 10 speed. Needed a new cassette for a new Hed wheel. For $XX, these are incredible deal! The finish holds up really well, too. Seems to be more durable than Dura Ace for a lot less $ and just a little more weight.
Shimano knew that the Ultegra 6800 cassette would reside as the heart of the new 11-speed system, which is why it devoted considerable time on a feature known as 'rider-tuning.' What this means is that you receive an updated range of useable gearing options with the advent of the 11-speed design.