Mind you, I'm saying this without the benefit of having seen any clips featuring the parents, but I'm not getting the vibe that Gumball's dad Richard is going to be a jerk character; judging by those character descriptions, it would seem that those neighbor characters, the Robinsons are the ones set to fill the show's jerk quotient. They kind of remind me of the Bigheads from Rocko's Modern Life, only they're both jerks.
As for the dad, the impression I'm getting from him (again, I haven't seen any actual clips of him in action) is that Richard would seem to be a lovable teddy bear sort of guy, like a John Candy character. So I'm not all too worried about his character being negative. This however:
...is a genuine concern of mine. I too really hope that the mother's being the working parent doesn't mean that she'll be the least seen member of the family. True, the parents' roles here are reversed as is the case on Johnny Test, and in the case of the latter show the mom doesn't appear as frequently as the other family members, but to Test's credit, the writers did a better job of getting the mom on camera after season 1. There were several instances where Johnny's mother could have or should have appeared, but didn't, however overall JT didn't do an entirely terrible job with the frequency of the mother's appearances. Out of Jimmy's Head did a far, far worse job with their mother character, who appeared so infrequently that she wasn't even considered a regular cast member. I'm really hoping that Gumball's mom Nicole (I don't know if that's really her name, but I'm going to call her that since no other name has been provided so far) will be an active and fun character who's seen as much as the father as opposed to her chief shtick being that she's never home. The pics I saw seem to suggest that the crew actually has plans to do things with the mother, so hopefully she won't be left out of the fun.