I highly highly doubt this will really turn out like Cowboy Bebop. The mood and atmosphere is just quite different... and it seems a lot less "adulty" and "stylish" in the style of CB. It feels a lot more subdued to me... which is not necessarily a bad thing.
I think if it's got anything to do with Mushishi it's the whole
harem tons of girls thing.
Ginko and Hei both have special 'powers' most others don't have and encounter people (mostly girls) in varying situations involving this 'power', and do something about it.
Meanwhile there are also occasionally other people with this 'power' and stuff... In Mushishi the theme is the whole Mushi world with the Kouki and all of that, but in DtB it's the contract, the fake skies and the Dolls and
kansokurei etc.
And DtB is obviously a lot more action-oriented, because while the Mushishi world has been like that all the time and is part of nature; the DtB settings have more of a "something happened and now it's like this, so we've got to find out the mystery behind it" - so one assumes there is a conclusion and something will be
done about it. Therefore the action... and of course there's much more rivalry among the people with the power.
And the other thing is how clearly dichotomous Hei appears to be (or is his real self treading a middle ground?) I think one scene that really got me in episode 1 was after Haraguchi/Shinoda ran off after teh park encounter, and his innocently surprised Li face - which felt so genuine - morphed into a suspicious, dark Hei face. That really said a lot to me. As a silly fangirl it worked perfectly on me because I was really going with the flow and being all excited and
swoony over him and then to realise that all that could have just been a complete facade...
...Maybe he's an evil Ginko in modern times with a mission to fulfil. Yeah.