I get where you're coming from. As an overall perspective, no Barney is not a good person in the slightest, he's a terrible misogynist and manipulator...

But Obviously you did not watch the show closely enough, cause, from a sitcom perspective (which is all fictional mind you) Barney and Robin were in fact a great couple! Robin is the first girl that made Barney want to change who he was. The love Barney had for Robin was in fact real and there was no way he was gonna cheat on her.

No there is no excuse to what he has done to other girls, but you can see real character development from him whenever he was with Robin or trying to get her. Though I say Nora and Barney were a better match because he went through the most charcter development and really gave it his all tryna get her. I think it was a slight mistake making Barney and Robin a couple for a second time (even if The Robin is my favorite episode and makes me cry each time I watch).

But even with that mistake, you can still see who Barney really is as person behind his horrible actions which in turn makes you root for him, which is what makes his character development so great.

Btw, for all the time he had a girlfriend and cheated... it was WITH Robin, which just tells you even more his feelings towards her... They were a great couple and made sense together as she brought out the best in Barney.

I suggest watching the show again and paying attention this time