The beginning is sooo boring. It takes over a hundred pages for them to even get to be at the same place at the same time where something even could happen. I gave up right at that point, which supposedly is when it gets good.
That said, excerpts from the book stand so incredibly alone. The Grand Inquisitor speech, the Father Zosima passage, Mitya's troika ride, Ilusha's funeral...
I found The Idiot a far more approachable book.
My copy of Master and Margarita has such incredible endnotes, without which I really dont think I would have appreciated it.
My Penguin Classics copy of Karamazov just has very short translation clarifications and didn't really improve my experience.
I understand why you might think i meant abridged though, since I was saying that the book is a slog but that it had great passages. I personally didnt mind the length as much as I felt I wasn't getting the most out of the "boring" parts.
Tolstoy on the other hand, Anna Karenina I binged and had done in like a week (on vacation, reading a good portion of my time)