if your goal is to just loose weight, then i don't think it matters where the carbs come from.
if you're trying to be "healthier", nuts are really good for ya as are veggies. But the thing is, the bars have a lot of fat and this is a high-fat diet whereas veggies have like zero fat. The bars will also boost your protein a lot. And the bars are more convienent. Personally, i prefer the shakes, but that's just me