I think the difference so far is that even after the first BoB episode "Toccoa", you started to get a feel for the characters and how they interacted. So far with "The Pacific", the only way I've felt I knew who was who and how they related to the other characters was because I've read their books. I don't see how they're going to be able to develop the characters and their relationships to each other like they did in BoB. Battles and people are too spread out in both time and space (Guadalcanal, Cape Glouster, Peleliu, Iwo Jima and Okinawa. Fall 1942 to spring/summer 1945; about double the time frame covered in BoB) and so far the tie-ins between characters are more confusing than anything, especially for those that aren't already familiar with the characters.
Ditto for the some of the major events. I'm glad that I already know what is going on, because the events are not really explained. How would anyone not already very familiar with Guadalcanal understand why the Marines went inland and then fell back closer to the beaches? The Battle of Savo Island was interesting, but I thought fell short on how the Marines felt about being abandoned by the Navy. They also failed to mention the landings on Tulagi, Gavutu and Tanambogo. (My stepdad was a little miffed about that because his dad was on Tulagi.) Heck, the landings on Guadalcanal were originally planned as a supplement to taking Tulagi and the nice harbor and seaplane base that was there!
Strangely, given the lack of explanation of the overall picture, they got the details just about perfect.
Still, I thought the first episode was a reasonably good start. Personally, I would have dropped the newsreels, maps and Tom Hanks voiceover at the beginning in favor of a little time spent explaining how the main characters got involved in the Marines. I think everyone understands the Japanese attacked Pearl Harbor (heck they even still teach it public schools, so it
must have been important!) and pretty much had their way for the first 6 months of the war.
I'm certainly looking forward to Episode 2.