CanadaOhMy

Depends on the question many times. If it is not 'I need help with my immediate reservation' you may not get a quick or a response at all.

I'd tweet them again noting it was a second tweet.

RNE

If you are @wandrMe, you get a sycophantic response from @united almost instantaneously. Seth is da man!

In The 216

I've had a generally positive experience with them although I think it's gotten worse as of late. I am guessing much of that is just the shear volume of tweets and requests for help they are receiving. Two years ago I could tweet them and get an immediate response and they would do just about anything you asked them short getting to fly the plane. I think the volume of tweets that they receive has exponentially grown.

I have noticed that they make it a point to respond to every tweet that mention's United, especially in a negative way (delay, lost bag, etc.), asking them to follow and then DM. If you need immediate, like truly immediate, assistance then Twitter isn't very advantageous most of the time. If you're trying to snag the last seat on a flight you're definitely better off calling because by the time a Twitter agent gets to you I would think your chances are slim of that seat being available.

Interestingly, I had a very comical discussion with a surly Premier desk service director who was scolding me for taking "advice" from someone on Twitter. I asked her if she knew that United had a whole social media team that handled customer issues, etc. and she said "no, but I am going to look into it."