I just finished the season. Most of the other characters were more interesting and less annoying (yet mostly still annoying) than Piper. Off the top of my head, I only ending up having a positive opinion of three characters Lorna Morello, Susan Fischer, and Cal Chapman. The rest were neutral (e.g. Sister Ingalls) or negative (e.g. pretty much everyone else). That's not to say they couldn't be entertaining and/or funny. Pornstache was particularly difficult to watch, but had his moments mainly due to how hilariously sleazy he can be. Nicky was okay, but had her I-want-to-punch-you-in-the-face moments. Often, the characters were all over the place, lacking any and all consistency. Maybe that's why thy're in prison.
I get it. They're trying to show prison culture, how the different groups interact and it's true that there are definitely people like that, but I still had trouble relating to most of the characters. I don't think I'll like Jason Biggs in anything.
Out of the 13 episodes, I only consider the premiere and the one about the chicken to be bad, in the latter's case, I just didn't get the point and it seemed like filler, like the fly episode in Breaking Bad (though even that was more entertaining than the chicken episode).