CNBC offers decent insight if you want a general overview of market conditions, reports on economic events, and if you don't mind hearing the different analyst perspectives.
However, if you're relying on those "Breaking News" bulletins for trades, then it's often too late and it WILL hurt your trading.
You'll notice the smart money was already made when CNBC finally makes its pitch.
So for having it run in the background, yes, but to rely on it for trades, forget it.