I want to start off this review with the positives, because there is a lot to like about the pilot. Christina Applegate and Will Arnett are wonderful in their roles, Reagan and Chris, parents raising a baby. Both are very human, warm, and likable. The show isn't overtly funny, but there are laughs to be found, and plenty of charm between the two. If this was all Up All Night was, I'd be very happy and looking forward to next week's episode. But there's a reason why I'm saying this first to emphasize the positive: the rest of the show doesn't work.
The other half of the show, the workplace and Ava, is awkward and needs significant retooling. Reagan works for Ava, who is supposed to be like Oprah, except her behavior is a bit... off. We never get a sense of who Ava is, what makes her popular, or any reasonable exposition on her character. What we do get, however, is a popular talk show host who's crazy, parties a lot and is in a lot of scenes, a mix which doesn't make much sense--the kind of thing you'd see on a wackier comedy. Except the parts with Reagan and Chris, aside from the cussing, are not wacky but sweet. When Ava shows up, she disrupts the flow in an unsettling way.
From what I've read, the producers bulked up Maya Randolph's role due to the success of Bridesmaids. Apparently she had less screen time and was a PR executive. Sadly, the producers' willingness to compromise commercialization for creativity came at big loss.
Pilots usually focus on the main elements before the show expands later on. There is a greater focus on the main characters and only a glancing look at the other characters. In the Up All Night pilot, Ava is about as important as Reagan and Chris, indicating she is not one of the other characters but a main character. While she may be a big factor in keeping them "up all night," there is a distance to her, stemming from her zaniness, that makes her far less appealing and intimate than a baby who keeps them awake.
Up All Night could have a been a great show--a quiet, understated comedy without big laughs all the time but having a nice charm. Instead, it's half of a great show and half a show which features a brash, Oprah-esque talk show host. Without committing to either, the show comes up short when there was a clear option which way to go.
Score: 8.3/10