Depends on the album. I found 8vm extremely easy to appreciate in the first/second listen, although it was my first DT album, I already felt familiar with the song styles and structures. On the other hand, the first disk of SDOIT was extremely hard for me to digest, I refused to fully listen to songs like "The Great Debate" for months! ToT was also very hard for me to appreciate since I was always told it was a bunch of mindless metal, I only got to appreciate it after reading a review and going through all the songs separately 1 by 1.
However, I was a n00b at music back then, I think I'm fully prepared to take on ADTOE in a more mature way.