When they were serving food, before 9/11, F on HP's A319s and A320s was a very nice product indeed. New airplanes, big wide leather seats, plenty of attention from motivated FAs, liberal upgrade policy.
Without food there's not much "product" to point to... cocktails aren't even served in proper glasses anymore. It's two drinks, two envelopes of trail mix and the FAs disappear for good.
The east coast services (JFK-PHX, etc.) are where the 757s are workhorses and while there is some food on some of those sectors now, I understand, the airplanes are far older and in less excellent shape. My family flew PHX-DCA and BWI-PHX a few months ago on 757s and said they were real rattletraps.