It IS a real challenge. The people who call it “easy” are people who who can already read beyond that level of Japanese!
I have read vols 1, 2, and most of 3, but could only do it with the aid of the vocab lists and the threads here on the WK community.
There is no vocab list for vol 4 and no plans by the good people here to create one, so the level of difficulty is about to sky-rocket for me now!
But reading those first three volumes was an amazing and helpful experience and I really recommend it!