Funny, I never thought much about her either way. But thinking back I think she played the role well. She's bland by design, just like Walt's car, house, neighborhood, furniture and personality prior to becoming Heisenberg. She fits perfectly with his old boring life, though she's arguably hotter than would be realistic.
It seems weird to be annoyed by her because you're rooting for Walt to go full badass. If he got a divorce and bought a screw pad with a huge pool and just tapped poon all day, you've taken away the conflict and tension that makes the show interesting. He's straddling two drastically different lifestyles and screwing them up badly at different times along the way, which creates all the suspenseful/dramatic/funny moments on the show.