As for whether you are a sucker, I think not so much in this case. I think you were more just unlucky to get the old seats. If you had gotten a new seat, you would have been about as well off as any other airline in C class for TATL.
Of course, for TPAC business class, there are MANY better options and I would never fly UA in C class on my own dime.
And if you have the $$$ for real international F, then you would be INSANE to buy UA. INSANE!!!! LH F is truly fantastic for TATL. Hell, any international F is better by far than UA.
But for TATL C, UA is about as good as any other option I think. Great seat, OK service, terrible food. Averages out to as good as the options.