I'm one of those that loved the original movie this TV sitcom is based on.
If it weren't for Will and Andy's characters, this show would be a total flop.
The Marcus character just doesn't work. At all.
And, Fiona's character is ridiculous. What made the movie dynamic so great is that Fiona, in the movie, looked the part (and acted it). A single mother, with issues (in the movie she was bipolar/manic depressive with suicidal tendencies) and could not hold down/handle a job very well. They lived poorly, and struggled. It was more realistic.
The Fiona in the TV is a joke. A single mother can move to San Francisco without a job, afford a nice home, and VERY expensive clothes and jewelry. It's just a TV show, yes, but come on. Designer clothes from head to toe, and every scene a different set of clothes. Covered in jewelry. One big placement ad campaign.
Somehow Fiona and Will live next to each other. Will was/is wealthy from royalties. In the movie he lived in another part of town, in a nicer place. In the TV show, they live side by side. What? You cannot tell that one is supposed to be bad off and the other living off of royalties.
Will and Andy's relationship is funny, and really helps make the show. Some of the scenes with Andy's kids (and wife) can be very funny.
The show pushes Marcus to be much more adult than he is, which doesn't work. And, all of the lines are delivered the same way.
Fiona is not projecting anything. Take away her accent, and she would be one boring actor in this slot (as much as I've liked her in the past, sorry, she doesn't even seem to be trying).
What is also funny is the original movie only received a 7.1 here on IMDb, while this TV show, with so many shortcomings, received a 7.6 at this point. Perhaps it will go down over time. As far as I've read, it has been renewed by NBC.