This cassette shifts smoothly, lasts for many miles, and has useful gearing. Ultegra is high quality and a good value. I have always been happy with Shimano components.
This 12-27 cassette helped more than the stock 12-25 in climbing hills, but not enough, and I got an 11-34 with mountain bike derailleur to do the trick.
I manage to climb just about any hill but slowly and only with great effort.
I got this 12-27 cassette as I through it would make climbing easier than the stock 12-25 cassette. It did, but not nearly enough, so I got an 11-34 cassette and mountain bike derailleur to handle it. The combination did the trick. I'm still no faster on the hills but this gearing definitely is easier on my legs.