When Sci Fi’s Battlestar Galactica premiered as a miniseries in 2003, it didn’t arrive with many high expectations. A remake of a cheesy 1970s series known primarily for being a Star Wars rip-off, from the network responsible for innumerable hokey TV movies, aired first in the U.K., Battlestar sounded like something that would be instantly forgettable. But the miniseries ended up premiering to strong ratings and even stronger reviews, and paved the way for a regular series that has been consistently one of the best shows on TV.

Now that series is coming to an end, with a two-hour final episode airing Friday, March 20, at 9 p.m. on Sci Fi, and its 10-episode final half-season has been a study in subverting expectations for the end of a long-running series. Like most serialized dramas, especially those with genre elements, Battlestar has a million unanswered questions, and like many serialized dramas, it also has one big goal toward which its characters have been working since the first episode. That objective—to find the mythical planet Earth after the 12 human-inhabited colonies have been destroyed by the robotic Cylons—was reached in gloriously anticlimactic fashion in the midseason finale, and the final episodes have been all about how to go on when your one beacon of hope turns out to be worthless.

This is a little like The X-Files’ Agent Mulder finally discovering that the aliens he’d been searching for his entire life were just guys in rubber suits, and as such it’s made the final batch of episodes a little unfocused. The thematic power of following characters who no longer understand their purpose in life has been tempered by a number of episodes that just felt like marking time, especially frustrating when a show is this close to its endpoint. While the crew of the Battlestar Galactica may have reached Earth and found it an uninhabitable wasteland, there are still many mysteries left to solve, and it’s not clear that even a double-sized finale will offer satisfying conclusions to all of them.

The show’s creators have always been up-front about making things up as they go along, though, and Battlestar’s strengths have been as much characterization and allegory as grand mythology. So an ambiguous or open-ended wrap-up would be in keeping with the overall tone, and would probably please the show’s fans who appreciate not being talked down to, even while possibly annoying those who want everything tied up nicely. Either way, it’s bound to be as challenging and genre-defining as the rest of the series.