Reputation is still in BD, but it has much less of an effect. Reactions to stealing and individual opinions were cut in favour of better enemy AI, IIRC. With the game in separate acts the only NPCs it would help to build up your reputation with would be the BF merchants, in any case.
Merchant prices are proportional to your reputation (unlike in DD where prices dropped as your reputation increased). This is either to compensate for gold being easier to come by as the game progresses, or an encouragement / temptation to be evil.
For DD2, there have been a few suggestions to make the reputation system more elaborate, so different species, guilds or other groups would have a separate base reputation depending on your species or actions.
