IMHO 'gainer' supplements have their place... its still a 'supplement', not a end-all-be-all solution.
Everyone wants the 'one step, silver-bullet' solution for gaining mass/muscle... but there just aint one.
Im not a trainer/doctor BUT I would say, stick to the basics first ie. increase your caloric intake with a balance of good lean meats, making sure to balance it with lots of good dark green veggies, fruit + fiber (gonna need fiber to move all this stuff through your system).
(people always make the mistake of just increasing their protein... but you gotta do it all so that its all in balance).
So when u eat a meal, increase the proteins ie. add another hunk of chicken breast AND up the greens ie. grab 2 handfuls of baby spinach + 1/2 cup of beans.
Its REALLY easy&cheap to buy spinach by the bulk batch and canned black/kidney beans are cheap.
Wash & salad-spin in batches, store in the fridge.
Right before you make your meal, reach into the fridge and grab 2 handfuls... open a can-o-bean, rinse, nuke...
Blamo, fast easy and most importantly... balanced.
A shake supplement makes sense when you cant get the real stuff... ie. right after a workout but IMHO its NOT a replacement... you gotta add real 'substance' to your input to put real substance on your frame.