Modern Family is often funny, but the more episodes you watch, the more you see how much the plots repeat. First, the problem is introduced at the beginning, escalated in the middle, and then solved immediately (usually by Jay), at the end. I call it the Modern Family Formula.
The characters can get pretty annoying, especially the Dunphys. Haley and Claire are very unlikable and never make me laugh. Cam and Gloria can get a little annoying too, but they're still pretty funny.
Overall, it makes me laugh, but the weak writing gets on my nerves.