Unless something major happens later on in the game, unless there is a Dark Souls style "Ah Ha! I need to read the item descriptions!" moment I'm guessing plot is one area reviewers are going to come down hard on. With all these years of development, all of the creative minds gathered to create this game it had to be deliberate right? This is how they decided they wanted this game to be?
Did Bungie really spend all this time on setting and lore building and not bother to write a plot? Why the heck am I running around doing MMO fetch quests? Why am I listening to Dinklage-Bot and Johnny no face? Why should I or my character care about any of this?
Its not just the lack of traditions storytelling, there doesn't even seem to be an attempt at Ico/Dark Souls style environmental story telling. So far every character in the game could scream WE ARE BEING MYSTERIOUS in your face and you would have much the same experience.