I haven't read it yet, that's why I was wondering if I should get an old version or the TAN one.
The original 1967 edition is available but it's a lot more expensive than the others.
There is absolutely nothing wrong with the TAN version. Save yourself some money and get the TAN reprint.
TAN Books & Publishers -- especially before 2009 -- had a spotless reputation for being completely Trad. I shouldn't have to even say it -- TAN is (was?) about the most trustworthy Catholic Publisher in existence after Vatican II. For the longest time, they were the ONLY exclusively Trad publisher. That's why they're still so big today.
The owner of TAN Books, Thomas A. Nelson, started an independent Trad chapel in the early 70's. That should demonstrate clearly enough where he stood on Vatican II. And he was the publisher/editor of all the books he chose to reprint.
He started an independent chapel even before he found a permanent priest to say the Tridentine Mass there. For months, parishioners would meet and say the Rosary.
Mr. Nelson acquired quite a collection of pre-Vatican II books from various convents, monasteries, and seminaries that went under. He still has them, although he lost ownership/control of the business in 2009.
Until the 1990s, most TAN books were photo-typeset. An old, out-of-print book was "destroyed" so each page could be placed on a very expensive scanning device. Printing plates were made from these scans.
An interesting anecdote or two:
The last summer I was a seminarian, we were driving by Rockford in our bus and I convinced them to stop in Rockford for breakfast. I made a call and pulled some strings, and arranged for a tour of TAN Books! We drove over and had an interesting tour. They gave each seminarian around 14 free books! I remember I received "substitutions" for many of them, because I already owned a lot of the books they were giving us.
Also, around 2002 I spoke with some of my contacts at TAN, and got them to donate 3 large boxes of books to the STAS library. A great infusion of solid, Traditional spiritual reading, especially lives of the saints! Imagine how much good that will do long-term. TAN was quite the apostolate; really a great mercy of God.