At Oak Ridge we've recently started a series on Reasoning from the Scriptures with Catholics by Ray Rhodes. It's a fairly interesting book, and I'm about half-way through it so far. The book is a well-written overview of some of the principle Catholic beliefs and why these often do not jive with Scripture, and while it can be read straight through it also serves as a nice reference resource when you need to look up certain topics like the Apocrypha and so on.
The only thing notable absent from the book, that I would have liked to have seen more information about, is the topic of birth control and family size, but I have a feeling that Rhodes deliberately avoided this topic simply because it is such a massive can o' worms. The dichotomy seems to be one of: most Protestants settle for "two kids and a vasectomy", while most Catholics find curious loop-holes like NFP (or just blatant disregard of papal teaching on birth control), and in both scenarios the Biblical mandates to be "fruitful and multiply" are more or less dismissed as contextual (or inconvenient.) I would have liked to have seen this issue covered more. My own observation is that in recent history there was a trend of seeing "large Catholic families", but I think this practice was based more on papal-writ on avoiding birth control as "evil", and not as much on the Biblical blessing of a full quiver (Psalm 127.)
Yet to me, when I consider Roman Catholicism, although I consider such a tremendous amount of their teaching so heretical and contradictory to Scripture, I do admire their strong pro-life position, which often feels more vocally powerful than that of the protestants. I also respect how Catholics often seem to have stronger grasp on Church history and the writings of the early church fathers, a study that it would do many Protestants good to investigate further. But beside this, there can never really be true ecumenical union with Protestants and Catholics because at the core of true Biblical Christianity is one key, consistently backed by Scripture: Salvation by faith alone, in Christ alone, by God's grace alone, according to Scripture alone, for the glory of God alone.