I've read Leckie's autobiographical Helmet for my Pillow years ago and the way The Pacific is trudging through each episode, is becoming faithful to the book from where it was based. Leckie's narrative is both funny and tragic, though he peppers it with euphemisms he coined his buddies in his unit. I think personal accounts differ tremendously from historical accounts (by way of detail, historians like Stephen Ambrose or Cornelius Ryan tend to divert from the humanistic point of view of the war and into the specifics of strategy and the actual combat, which Band of Brothers or The Longest Day depicted).
Eugene Sledge's book, I haven't read, but is next on my reading list.
I kind of liked Part IV, by the way, even if it lacked the "giveaways".