"Overwritten" means for me that the textboxes are longer than they need to be (more descriptions than necessary, too much adjectives etc.), but in this case they seem to use their words economicaly. So at least if you not like it, it will be not because there is too much padding.
As for the rest: You do know, that different writers have different writing styles do you? With seven authors there should be at least one whose style you like. More interesting is, what the writers did before DO:2 ,how experienced they are in formating text and if they were involved early on the process (which a lot of writers aren't. No really, many companies create the levels first and THAN add the story, that holds the story together) or if they have the bloody time for it. The quality of the writing depends on so much, but the amount of text isn't the biggest issue. It's more work for everyone, but saying "1 Million words are destined to be shit" shows me, that you were never part in any writing progress. You can write pure gold with a million words, as long as everyone (the writers, the designers and the editors) are on the same level.
We should also take into account, that one million words in D:OS2 may not be the same as one million words in Numenera. Mostly, because we play more than one character and the wordcount adds up because they may use the same sentence more than once, but adress a different character.
Example: "You there human/dwarf/elf/lizard/Undead." Same sentence but every time a character is adressed differently and this counts too. Add maybe now the sex of the character and a slightly variation of the same sentence (can happen too) and you get your 1 million words and not because they writers are so much in love with their writing. Small details, yes, but they should be taken into account.