Final seasons and final episodes of long running series are difficult to get right, even when they're planned (rather than just axed). Many have been good (e.g. Buffy, Sopranos, Gilmore Girls), some have been disappointing (e.g. X-Files, Alias, Millennium, Angel), but only a few have got it really right (West Wing, M.A.S.H). Galactica gets it spot on.
Considering how many sub-plots and themes, and how much mythology had been built up over the years, finishing this complex and often bewildering series was always gonna be a tough job, but you can tell this ending was planned long ago, and it finishes off the series perfectly.
It took me a while to discover the new Galactica, having dismissed it as yet another second-rate just-for-geeks sci-fi series. But after hearing only good things I finally bought the pilot movie early last year, and was so astounded by the quality of the writing, acting and sheer drama of the story that I bought the rest of the series instantly and have watched it over several months. So, I'm not too bothered that they have released the first and second halves of season four separately, because, although shorter, they felt to me like two separate and distinct seasons, the first half having it's own surprise ending, and the second feeling more like 'season five' because of the break. I'm quite happy for this to be simply called the 'final' season, and to sit separately from the first half.
I hope, and tentatively expect, that Lost will end just as well as this did.