Some people got all pissy about certain elements, because it didn't follow what they wanted out of the show.
If your focus is all about the sci-fi, and you get annoyed with a few "wait... huh?" moments due to odd directional shifts in the plot arcs.
But I absolutely enjoyed every moment of that series.
The very last episode wasn't the most satisfying ending to the overall story, but it felt as if it really could have been worse (or more annoying: by not even daring to provide an all-encompassing end). Even so, my opinion is this: if 99% of the ride is enjoyable and satisfying, but the very last moment of the trip resulting in a funny taste in your mouth - would you say "I wish I never partook in that adventure" ?
There have been many stories (TV, Cinema, Novels) that were amazing every step of the way... until the final moments. Not entirely satisfying ending, sure, but an enjoyable ride nonetheless.