I have finally, after reading The Giver about 14 years ago, finished The Giver series! Granted, this only came out two years ago.
This book tied together the story started in the Giver and the communities we saw in Gathering Blue and Messenger. I liked going back to the community where it all started. I didn't reread the Giver beforehand. I think I have reread it since I first did, but not recently enough that I remembered a lot of it.
For example, I didn't remember what her son's name was, even though you did learn it in The Giver and I liked seeing Claire finding it out.
The book did drag a bit, but I enjoyed it overall. It may have wrapped up a bit too cleanly, but I think it worked.