There's two things to consider when evaluating this card. If this were simply a 3/2 draw a card for 3, would it be played? Since drawing is typically evaluated at 1-1.5 mana, I'm inclined to say yes. Now, is a card from your opponents deck worth 1.5 mana typically? No. It doesn't fit your game plan and your strategy to win typically. but this is a discover effect and you get to know 3 of their cards. This feels like a really solid card in any match up that's not vs aggro.