I personally think BSG works best when it's in serial mode, with each episode feeding into the bigger picture. Perhaps it's because nearly every new US television series follows this structure (24, Lost, Heroes, et al), but BSG's standalone episodes often seem weak in comparison to its mythology stories.
Michael Taylor, a writer behind many Star Trek episodes, most notably the sublime Deep Space Nine episode The Visitor, spins a yarn that focuses on Lee, Starbuck, Chief Tyrol and Adama, using boxing matches as its macguffin. Unfinished Business looks to be skating on thin ice at times, but just about manages to make its idea go the distance.
The main plot revolves around Lee and Starbuck, revealing how their romance was rekindled on New Caprica and why it's now so frosty back aboard Galactica. In essence, the episode fills gaps in the character's lives, (as we skipped a full year between season 2 and 3), and it makes for an enjoyable insight.
The secondary plot isn't quite as involving, providing retrospective on Adama's relationship with Chief Tyrol and the circumstances surrounding the Chief's decision to leave Galactica. This sub-plot is the most redundant of the two, but it does provide a startling boxing match between Adama and Tyrol.
Taylor's sense of characterisation is excellent throughout and the eventual climax to the show is poignant, although it's increasingly difficult to sympathise with Starbuck because her emotions are so haphazard! Sometimes she's an enjoyable and spunky heroine, but often she's just an annoying smart-ass.
As a character, Stabuck's temperament is the most difficult to write and her actions in Unfinished Business don't show her in a good light. To create such an emotional response in viewers is a testament to Katee Sackhoff's acting and Taylor's written word, but I increasingly find Starbuck a frustrating and annoying presence.
Overall, while Unfinished Business is very well-written and an interesring way to flesh out relationships, it still seems to prove my theory behind BSG -- as a show, it loses its narrative bite when it takes its eye of the Cylons. The characters work best when they're dealing with military and poltical dilemmas, not so much when they focus exclusively on the relationships. The depth of BSG's cast is fantastic and we need episodes like this, but I'd rather get insight into Adama, Tigh, Baltar and Roslin.
Unfinished Business is a good episode in terms of writing, character development and performances, but not one that held my interest because of my personal detachment from the Lee and Starbuck love story. However, if you're a fan of crazy Starbuck and nice guy Lee, add another star.