I bought a 10lb bag of NOW Isolate a while ago. The taste isn't bad, but it doesn't mix as easily as other protein powders I've had.
2 things I've found it very valuable for, especially when cutting.
Protein Jello. I can get two full scoops mixed into a small box of jello. Tastes exactly like regular jello. If you're cutting, get the sugar free jello.
Soup. I take a can of chicken soup, microwave it a minute. Stir in a scoop of whey with a little extra water, microwave another thirty seconds or so. High protein soup, you can't taste the whey.
But like I said, with NOW brand anyway, it doesn't mix the best. It's usually better to blend/shake it in a little water before mixing into anything.
Haven't tried it in marinara yet. Probably better off blending it with straight tomato juice before stirring it into thick sauce.