Flashback and graveyard decks just got the card drawing engine they needed.
The obvious first impression is that this card is a blue Burning Vengeance that draws you cards instead of allowing you to Shock things over and over. What I really want to focus on is something that I've already talked about in Drogskol Reaver and Jar of Eyeballs and that is until Dark Ascension, Innistrad Block was severely lacking in the card draw engine department. (If you think about it, the only permanent card draw engines were Mentor of the Meek, Sturmgeist, Bloodgift Demon, and Charmbreaker Devils.)
Secrets of the Dead is just the latest of these new engines and I have a feeling there are at least a couple more to come. But I'm sure this card in particular is going to see a ton of play.
The most obvious (and incorrect) deck to throw a pair of these into is a standard Burning Vengeance Deck. It's incorrect because Burning Vengeance doesn't need it. If there's one archetype in Innistrad that doesn't need additional card draw, it's BV Decks. They already have Think Twice, Forbidden Alchemy, Desperate Ravings, and now they even have Faithless Looting. The common thread between those cards is that they also already have flashback on them. They actually enable themselves and every other card. And this is something that Secrets of the Dead doesn't do.
I keep coming back to Gravecrawler not only because I like it so much, but because it really brings the point across. I think Secrets of the Dead would be best suited in decks that featured cards like Gravecrawler and had a slash of flashback. If you throw it into a dedicated flashback deck, you're just doing it wrong. It's not needed in those decks at all.