I don't know why UAL f/a's get such a bad rep. I fly United quite a bit, and I have never - and I can honestly say this - never have had an experience where a f/a was "surly" or rude to me. In fact, it's usually the opposite. I was on a flight in April 2000, and I ordered a beer because I had some coupons for free drinks. When I went to give the coupon to the f/a, he just waved it off and said don't worry about it. He basically just comped me for it. He could have been a hardass and insisted that he take the coupon so I couldn't use it again, but he didn't. I know that's just a little thing, but it's usually the little things that add up.
People also tend to blame airlines for things that they can't control - like the weather. If heavy snow shuts down ORD it's United's fault, or if fog shuts down SFO and you have to turn around and fly back to Orange County (happened to me), it's United's fault. People shouldn't judge an airline on things it can't control, but on how it responds to those things. In the first case, I was flying from CLT to LAS for the holidays, but ice and snow shut down ORD. What did United do? They got me on TWA to LAS via St. Louis, arrivng only about an hour later than I was scheduled to arrive had I flown UAL. Granted, most airlines will try to do that, but their supposedly "surly" counter agents could have said,"sorry, we can't route you through Denver because we don't fly there from Charlotte, I guess you'll have to try again tomorrow." In the second case, when we turned around and headed back to Orange County, they captain lifted the ban on inflight cell phone calls, so the passengers could call and make other plans. The supposedly "surly" flight crew could have said, "sorry, you have to pay an arm and a leg to use the Airfone."
But I will offer one criticism of UAL and it's this: they need to really get it together with their pilots and mechanics unions, and stop the shenanigans, like pilots calling in sick, and aircraft suddenly developing "maintenance problems."
Example: I was flying from ORD to LAS in November and I was supposed to fly that leg on a 767. When I get there, a 757 is rolling up to the gate. The pilot later explained that the 767 we were supposed to fly on got held up in Honolulu due to "maintenance problems." This was around the time that UAL and the mechanics were having it out. They need to sit down with both unions and work something out and cut the crap because it makes the airline look bad.
Other than that, United's a great airline, and as KonaB777 said, they're coming back.