They're amazing. I rode around the world with one and it was great. Had a spoke nipple snap and they sent a replacement hub body, all the tools I needed, and replacement oil for free to China. And they serviced it for free when I got back. It's a lifetime investment and will save money on replacing cassettes etc in the future.

They are expensive though and more heavy than derailleur setups.

Bike setup here: www.tombrucecycling.com/the-bike