So we've got three days left, and they've shown a video of the multiplayer customization options. Pretty badass, but we'll have to see if the gameplay makes the customization worthwhile.
It looks like there's a bunch of chapter/legion/warband/whatever presets and from there you can customize each piece of armor (So you can pick two different pauldrons, two different leg armors, etc, one for each leg. Looks like there's around ten "themes" and you can mix and match among them, most of them are pretty cool. Then there's colors and stuff, overall it looks like there'll be a huge amount of variation but you have to level up to get everything (Have I mentioned how much I hate when multiplayer shooters pretend to be mmorpgs?) Oh well, it'll be cool.
The preorder bonuses aren't customizable though, which sucks. They're just full skins. Steam's preorder bonus is blood ravens, which look boring. Best Buy gets Emperor's Children and Iron Warriors, both of which look awesome and Steam got ripped off. You still have the color scheme presets for the chapters you didn't get, but the preorder skins have all kinds of macguffins and such. Wolf Wolves skin has wolf wolf trophies and such, Black Templars skin has the tabard, etc.
Also, the bolters are done right. If you watch in slow motion the bolt goes in and then there's an explosion a split-second later.