I never have any clue about playing length - it seems that I am slow to begin with and I never clock my time anyways, so cannot answer the first question except with "there is quite a good bit of content", certainly more than many others.
There is a major story going on in the background, pushing to the foreground more and more as the game goes on. As is the thing with sandboxes however, it may need to take a break every now and then because you're preoccupied with earning money (not really necessary but you can buy some additional outfits for the girls, even if with limited use) or following some non-main-story girl path.
Also, there usually are more steps between meeting people and fucking than just a drink and a chat, at least the main characters have pretty pronounced storylines, as do most (but not all) of the more developed side characters.