i've used Uber many times, including from our hotel in Anaheim to John Wayne airport just the other day. never had any problems and recommend the service.
it's all smartphone based, so you download the app, set up an account, and then you can request a pickup using the map. once you request a pickup, you wait for a nearby driver to accept the ride, and then you can track how far away they are in the app. once the driver is close they'll give you a call to get your exact location and you're on your way!
there's different levels from uberX to uberLUX. uberX is the cheapest and you'd be picked up in a Toyota Avalon or similar class of car. uberXL would be a smaller SUV like a Ford Explorer, uberSUV would be a full-size SUV like a Chevy Suburban.
if you're looking for something similar to a limo service, you'd go with uberPLUS or uberBLACK which would be different levels of luxury cars. the one time i took an uberBLACK i was in a really nice BMW 5-class.
if you've never taken an Uber before you can get a coupon for $20 off your first ride by using a referral code. i'd be happy to give you mine if you choose to go that route.