Let me get something straight - I think liquid calories are a great idea if you need an ass load of calories. I just think that a shake should contain whole food as well.
Many weight gainers are cheap and nasty, basically bottom line proteins with sugar added in for extra calories. I would sooner get a good brand protein, and add in carbs from natural sources, like bananas, malt, honey, soaked oats, passionfruit, strawberries, etc. If you're lactose intolerant, use lactose-free milk.
I still use this mega shake idea with Classic Grow!. It's cheaper in the long run and better for you.
PS Tell your old man that Classic Grow! is a weight gainer. It's the best on the market.