Pros
Based in SFO for 5 years in my 20's. It was a great time in my life, met a lot of interesting people and got to see the world. Great experience to have on the resume, never ceases to impress and fascinate employers looking for people skills.
Cons
United's company culture is pretty negative/jaded. It has gotten better in recent years though. The job itself was fun, but totally exhausting. It wrecked havoc on my mental and physical health. The reality of the flight attendant lifestyle is hard to explain, one has to experience it to truly understand. I had hard core anxiety for most of it. This is a very, very hard job to quit (because there is nothing else like it), yet many stay despite not seeming truly happy. This effects morale big time. Personally, I needed more structure to live a healthy and happy life. I like going home to my own bed, cooking my own food, and not being taken out by jet lag.