Yeah he was, Rachel Menken is the one who asks about his children, because he comes to her wanting to run away, and his response is that he'll send them money.
So... at least he was willing to send them money, but that doesn't change the fact he was basically ready to abandon his kids.
To be fair him running away or considering that wasn't done out of maliciousness but rather because he was scared, but on the other hand he was being selfish and only looking out for himself, so I can understand why people find Don deplorable.
Although I guess maybe Don is getting better based on what happened at the end of S6?
Well he is a fairly different person from season 1. At the very least he is now open with those close to him about his past. That's actually a pretty huge thing. He still needs to improve a lot as a parent (an understatement) but I do not think he would even consider abandoning his children anymore.
It's also unfair to keep judging Don on events from a decade ago, anyway. No one who has tried to change should have to be held against actions from that long ago.
Don has grown, but he is still doing awful things. Not surprising in the least. Absolutely no one drops their shitty traits without backsliding. But he is trying to change, he has tried a lot to better, and deserves credit. It doesn't even matter how many times he was caught doing awful shit. Don on shown plenty of regret. Some one beyond redemption doesn't show genuine regret.
Don is not rotten to the core. He is not beyond redemption. At least not yet. We'll only know if he is a total shitbag come the finale. And he could be, I won't put that past Weiner.