Fundamentally, this card increases your hand size. So far, there's only 2 investigators where I've found the 8 card limit becomes a problem; Daisy Walker when she's using the Old Book of Lore each turn, and Rex Murphy when choosing to fail elder-sign tests, or using Search for the Truth.
For them, this card could be really useful. However, both can also take Dr. Milan Christopher, whose +1 and paying resources for investigating is probably preferable. He's a much stronger card.
However, at the right time, and with those investigators, this could be a useful ally for a part of the game. I think you have to see this as an ally you might want late in a game, similarly to how a Research Librarian is most useful at the start.
So, in short - possibly useful, but highly situational, and I'd only bother for investigators who can draw a lot of cards.
It's worth noting that in the Dunwich campaign you sometimes don't want to get too far through your deck, so getting a third of your deck into your hand is maybe not the best idea.