I agree Loretta Devine is a joy to watch. Even with the sub-par dialog she's given, she works wonders.
The plot is shopworn, but I wouldn't care if it were done cleverly. It isn't, but what really torpedoes this movie is the lackluster dialog, especially as the main character is supposed to represent a writer. I'm not speaking of those colorful explosions of verbosity that occasionally punch through--I'm speaking of all the exposition. All that dialog about who is where and why and how. It's as dull as donuts. The writer missed a lot of potential fun with words, I think.
I also think this film suffers from poor editing. There is a lot of slow cutting, probably for anticipated laughs, but the situations rarely generate the laughs to fill up the time. Not from me, anyway. Truly, I think cutting 15 or 20 minutes out of this film would help it a lot.
The performances are generally good, though I thought combining over-the-top caricatures with low-key realism made for a confusing mix. Pick a style and stick to it.