UK/Manchester (home) UberX
There's almost always an uber available at the airport, rarely at Stockport station. Uber in the UK is registered as a minicab firm employing minicab drivers. Drivers tell me they are paid more than working for other firms, and the fares are cheaper

UK/London UberX
Never had a problem here, again minicab firm, far cheaper than black taxis, and for a couple of people a similar price as the tube for travel in zone 1.

Singapore UberX
I think there's an $8 minimum, meaning that for short trips in the CBD a taxi is cheaper. Uber tends to be available even when it's raining and the taxis are full up. I'm staying for a week in Hougang next month and plan on using Uber a fair bit to commute, at least on the way back from the CBD. I've had two drivers independently concerned that automatic cars would take over their jobs soon.

I got Uber from the airport once, however last week failed to get picked up - not sure which floor the driver was on, but he wasn't on the same as me at T3 (There's multiple levels)

There's a taxi option too, and for a time even a lambagini option with a minimum price of something like $200, that

Sydney UberX
Had a really grumpy driver here who didn't like the fact I had a foreign phone, otherwise no problems. Uber works fine in the CBD.

Berlin
Sadly doesn't work

Frankfurt UberPOP
This was fine, about 60% of the taxi price the night before

Brussels UberPOP
Far cheaper than a taxi, and most taxis refuse credit cards. Went from EU Parliament to Airport in rush hour a few months ago, took 57 minutes, cost €21

US/Los Angeles UberPlus
Uber Plus from the airport about 2AM in January, nice big limo, US$56 to downtown.