I really enjoyed Under The Dome. Between the characters and situation, and pacing, I thought it was quite astute.
However, it seems the ending was very polarizing in terms of opinion/reception. I personally don't think the very specific portion of a story that is the ending, should make or break it, as quite a few critics/detractors tend to argue against such cases. Personally, I also didn't mind the ending - for the entire story, it really wasn't an easy concept to sell in any fashion, but leaving out an answer (like some argued) really would have been a major cop-out that critics would have rallied against anyhow. The rest of the novel was a very enjoyable read and kept me glued and satisfied... much the same as Battlestar Galactica (newer series), something many people said the ending sucked so much they basically suggested not to even watch the series. I don't get that opinion, I guess... even if an ending isn't a satisfying conclusion, can one argue against the rest of the enjoyment provided by 99% of a story?