"Business as Usual" was not business as usual. In fact, it was completely the opposite. The episode was, unlike any other before it, built around a story with a personal connection to all three leads, which explains why it did very well. But ultimately, the reason why it came very close to becoming the best episode to date is simply because much of what happened advanced the overarching story arc in a dramatic way.
After watching the episode, I can comfortably discuss the story now, but when things started rolling, there was no clear sense of convergence in the various, apparently unrelated events. At first, the hour did not seem to start that well. To me, a man collapsing and losing all the water in his body in a few seconds doesn't have the same visual appeal as, say, a house being consumed by a fire (without flames) in a few seconds. The second image is fascinating without the creepy details (people inside?) jumping to the viewer's face. Being used to creepy doesn't mean watching it with indifference. So, when we move from the dried out body to a conversation apparently shelving the shooting (and subsequent death) of a major antagonist in a couple of sentences, we don't necessarily think we are on our way to a memorable hour.
Fortunately, things got better. It was about time Nathan Wuornos showed some passion and determination. Until these events, Audrey had gradually (though unofficially) taken over from the previous chief, nudging Nathan into accepting whatever she wanted. Nathan, as a character, has always been drawn with subtle strokes, nothing too obvious. This is why, after being so passive for so many episodes, it was good to see him expressing his feelings in more ways than one: pointing out her carelessness very vocally, helping her find Lucy Ripley, and strongly hinting that he cared for her. It was also good to see him embrace his troubled side.
I am right there with Shepherd Book (Firefly) who thought there was a "Special Hell" for child molesters and people who talk at the theater. However, when Audrey and Nathan looked at each other so intently, I yelled (in my living room) "No kissing!" and I was relieved when she stepped away. Unfortunately, the writers then dragged her back to him for the kiss, which was wrong. This was the time for significant looks of gratitude. The kiss would have naturally come later, not in the episode following her break-up, not so close to her being all unlike herself while expecting a visit from Chris Brody. This is a typical case where the introduction of a significant recurring character (Jason Priestley's Chris Brody) has intruded upon the natural development of a relationship, which is now likely to be much less than it could have been. They will be together, sure, but with less magic.
Fortunately for the episode, there were many other, more positive, aspects to the story. With Evi now gone, Duke was paired with Dwight, a character almost every bit as likable as Haven's resident bad boy. They led us through their fight, their bonding and their quest with ease, like characters who know we have no other choice but to like them, even when blood was spilled. The bit about Duke's dad giving his son a boat was very well written. Even considering that Duke could have sold or lost that boat without discovering what was inside, it was still enjoyable. It was to be outdone only by the storyline's shift in focus to Audrey.
And of course, Haven cannot shine if Audrey isn't at the heart of the story. What happened here actually started in the previous episode after Audrey shot Reverend Driscoll. Her attitude after that event and this episode's conflict between Nathan and herself, as well as her recent personal reflections, showed some sort of quest for identity. It was only fitting that here she actually met the original Lucy Ripley, the woman she thinks her previous identity was based upon. The meeting helped shed some light on Audrey's past and her role in Haven's conflict, showing how close she came to stopping it for good the last time. But, it also arrouses our curiosity on Duke's role, suggesting his "choosing side" could indeed determine the outcome of everything, especially if he kills Audrey.
Before this episode, Haven had never delivered a story which so significantly advanced the overarching series arc. Even considering its little defects, "Business as Usual" is more than just a good episode of Haven, it is an episode that cannot be skipped when discussing the series in the future.