To be honest, The revelation of Terry being Bruce's son was never much of a surprise, and im pretty sure plenty of people thought about similar things before. I mean, both his parents have brown/red hair and dark eyes, and here comes Terry with Black hair and blue eyes, just like Bruce. I mean, he looks like a younger Bruce, more or less.
I had no problem with it. Was it necessary? Not really. But is it any surprise? Not at all.
The episode could have been better made though. All throughout we get the black and white sequences of Terry being an idiot and a dick, and we are led to think that he has actually done those things before going to Waller's. And yet apparently according to the developers, those are not "past" sequences or flashbacks, but thoughts in Terry's mind. He feels like taking his anger to Bruce, he feels like he should stop seeing Dana, he feels like he should quit the JLU. But all he ever did, was break into Amanda Waller's home when he found out he was a perfect genetic match for Bruce's new kidney, and that apparently, Bruce might have known for a long time.