Yes, but that's not Year One, which should probably be judged on its own.
In any case, Gordon and Essen certainly had a great marriage for some time, that couldn't have happened without Essen being introduced. And since I can't remember any great stories or storylines involving Jim's wife except Year One, I'm inclined to think Essen was a good contribution and Jim's affair doesn't make him an irrevocably horrible dog, it just makes him human and flawed. His faults, in Year One, are no worse than Bruce's or Selina's, and certainly no worse than Flass' or the Roman's.