In terms of service, UA has some of the same bitter FAs and GAs you would see at other legacies, but on the whole, they are a thousand times more pleasant than US. I used to fly US a lot to CLT, and now I drive or fly UAX from IAD, even when US is cheaper.

UA also has the best IFE of any legacy, much better route selection out of IAD than US has out of DCA, and E+ is a good value on transcons.

UA still trails VX and B6 as far as overall service, but if you're a status seeker, they are easily the best out of the DC area.