All of the participants know each other, either organically or (more likely) by design of the producers, but they aren't forced to live together or given tasks to complete in each episode. Rather, they simply pursue their professional and personal goals, spending time in casinos and nightclubs but also in local parks, houses, apartments and neighborhood bars. The show presents a vision of Vegas as a real, well-rounded city, even if it promotes a few Sin City clichés, and for that alone it should be commended.
In a way, this show does what The Real World used to do, and what it ought to be doing again—it depicts people going about their real lives, figuring out what they want to do and whom they want to be as they navigate their 20s, while still making plenty of room for gossip, hook-ups and interpersonal drama. Since Paradise has been cast, presumably, for people in the same social circles, there isn't the level of diversity that you find on The Real World, and, so far at least, nothing so heavy as competing worldviews (unless they involve dating etiquette). There are also too many interchangeable blondes to keep track of at this point.
And therein lies the problem: As admirable as the show's effort to depict real Vegas life is, it still can't compensate for the utter vapidity of most of the cast members. Caring about which hot chick inarticulate rocker Rick will choose is next to impossible, and when the Cameron Diaz-looking Greta, a waitress at the Rainbow, complains that she's going to, like, be alone for the rest of her life, you just want to slap her.
To provide info without using interviews, the producers have various cast members deliver voice-over narration in an obviously scripted introspective style reminiscent of Ellen Pompeo's musings on Grey's Anatomy, another show about young professionals and the people they sleep with, albeit a fictional one. Paradise tries to capture that tone, combined with a little Sex and the City and a whole lot of glitz, and while the result is not exactly compelling, it's the truest depiction of Vegas life we're likely to see on TV for quite some time.