The original Battlestar Galactica always managed to alternate between amazing episodes and extremely poor ones. This, and the conclusion of the two-parter, are no exception.
Like the other best episodes of BSG, this one works well because it really fits the premise. What this is about is the trip home-- but at what cost? Should the fleet be willing to throw themselves to someone they hardly know, in exchange for hope and a possible passage home? But it becomes obvious fairly quickly, at least to Apollo and Adama, that Iblis is more than he appears to be.
Not as good as "The Living Legend" by any stretch, but this is precisely what makes BSG fun. (Even if it gets preachy at times.)