I watched it recently and thought the same, lot of mindless action in the first few eps, don't really know/care who anyone is (Band of Brothers set up brilliantly for this by starting in training camp). Becomes more interesting when it slows down and delves into the character stuff more imo.
It might be easier to follow if you bear in mind that it revolves around 3 protagonists:
1. Robert Leckie, author of the memoir "Helmet for my pillow".
2. Eugene Sledge, author of the memoir "With the Old Breed at Peleliu and Okinawa".
3. John Basilone, archetypal MoH winner.
Band of Brothers was based on a single book about a single group. The Pacific was based on two books, plus Basilone.
Personally, I'd have preferred Basilone left out, and focused on just Leckie and Sledge. Sledge's memoir in particular is very vivid.