Has anybody used it? What's your experience like? If applicable, how does it compare to US?

Excellent. Uber X is very good value for money. Just watch out for the surge pricing though.

I did the fare estimate and it was about the same as taxi.

I believe in hk its still illegal and their cars are not insured for fair paying passengers

In china uber cost less then taxi

I wonder if those people driving Tesla in HK was driving  for Uber.

I used Uber X from HKG to Wan Chai on my last after midnight arrival. Nice driver and straight to the Ozo Wessley(sp) hotel. $378HKD

I use uber a lot especially for "long" trips or cross harbour trips:
- cheaper than taxi
- better cars
- polite drivers
- they have a GPS so no need to hear the "EHHHHH?" when taxi drivers don't understand where you want to go

i've had a lot of trouble with the gps, though. drivers have a hard time finding me and i watch them just drive in circles around where i am.

Tried it a few time in HK and the problem is much like hapaguys experience, they rely too heavily on Google maps to guide them around town, so they don't have the knowledge of the roads.  Google sometime has them driving routes that are simply impossible somewhere a long the way, asking them to U-turn where u-turns can't be made.

Better cars yes, cheaper yes sometimes, pick up times are a little deceiving .

I like them better in HK because
-They are usually much nicer than cab drivers. Most cab drivers if you speak mandarin to them they are somewhat rude (maybe they think i'm a mainlander?)
-Cars are usually much nicer
-During non rush hour times its much more convenient

They are sometimes a pain because
-Most drivers are new drivers and dont know the routes
-They must rely on google maps to find you and get you to your destination
-Sometimes GPS signal is unreliable in the city (due to the tall buildings)
- Out of the 5 times i've used the service the driver either had trouble finding me due to being one street over, or if they miss a turn while driving me it could take up to 10-15 minutes to turn back around (depending on where you are).
- I've had a ride where the GPS signal was so bad the phone kept rerouting every 10 minutes. We ended up going in a few circles every time the phone got the signal back.

Dont even get me started on mainland. They are so desperate for drivers that the drivers get a bonus for X number of rides in a day. So they prefer much shorter rides. They will call you to ask where you are going. If you say somewhere that's more than a few blocks they will tell you that they were just about to get off and for you to cancel the ride. They wont cancel. They want you to cancel since they are not allowed to turn down rides. Most of them play the game until they get a lot of short rides for the day, get their bonus, and go home.

There are some nice drivers. The ones that are nice are really nice and legit. So it's kind of luck of the draw.

Yes, the GPS has more or less of a glitch. The problem is that depending on where your pin is. The software tends to associate the pin to the street it is closet to. However, I don't think you would have a problem if you enter the address manually.

I use it all the time, it's great no need to use cash and have detailed log of journey and account. Sometimes you get a free upgrade to an uber black as some drivers do both.