I've had gastric bypass so protein drinks were a way of life for me early out - I still have one most days because as a non-meat eater, I don't always get the required amount of protein in (half before my workout and half after).
Whey protein isolate is the better form but it's generally more expensive. But you have to be careful, the very nature of these supplements means that they often have vitamins/minerals added.
I do know that Unjury has no vitamin K in as I contacted them to ask. Peter didn't have much of an appetite when he got home and a protein drink helped.
If you're thinking of going that route, I'd recommend the unflavoured:
http://www.unjury.com/reg/nutrition.shtml
Made with milk, it'll give around 27-28g of protein. And if you get some Torani or DaVinci flavoured syrups, you can ring the change.
But you don't really need to buy protein supplements (unless you want the convenience when you're on-the-go).
Make your own!
1 1/2 cups milk (I use organic fat free)
1/2 cup cottage cheese (again, I do the ff stuff)
sling it all in a blender with some fruit - frozen berries work well, and just buzz it all up for a great smoothie. Omit the berries and use the flavoured syrups and ice for a change.
That'll give you around 27g protein a shot.