I understand and believe Catholic/Tridentine soteriology / doctrine of justification, but man is it repellant. I have to write an essay partially on it, and when it sits there next to the Lutheran doctrine it's so painfully bad. Not in the sense of innaccuracy or lack of Patristic support etc, but just sad, difficult, and scary.
When you read things about 'killing grace in your soul' versus 'Christ's free gift of salvation' and the overwhelming mercy of the Lutheran gospel, it sometimes makes you wish you could have all the Ecclessiology and Tradition of Catholicism and just take Lutheran justification... I guess that was the Anglican dream really.
Anyway, while it's easier and easier to read (Trent that is), it still strikes a bad note, it's all the 'worst' parts of Catholicism together.
By contrast I'm reading a book by Etienne Gilson called "The Spirit of Medieval Philosophy" and it's amazing. Obviously it's on a really different topic, but it's awesome how he describes the scholastics and how attractive he makes the doctrines rejected by the Reformers seem.
I've found out in Thomism too, they traditionally talk in a way about salvation and predestination that leaves little to free will. NOT that they deny it, or that St. Thomas doesn't write about it elsewhere - after all they firmly believe in it. But they err on the side of Grace and predestination rather than the side of free-will and foreknowledge.
They recognize that it's a mystery how free will works with efficacious grace, but they teach it. And that's the great gospel I always need to hear. That even when I'm completely sinful, Christ is still giving me grace, and has chosen me ante praevisa merita / unconditionally.
The one interesting thing I've found is that describing justification in terms of grace, merit, cooperation, etc is more passe now. It seems like after Jansenism the Church got stuck with how it could talk about it. Thus they've gone to the Greek Fathers and are now big on understanding soteriology through Trinitarian theology and participation in the divine nature etc.