The third book is a fine end - a bit rushed maybe toward the end,  but as it could really go on forever, one has to close it somehow. 

This one left enough loose ends not to be too simplistic but also gave a more or less satisfying resolution to the stories I started to care about within the main dystopia.

Year of the Flood is probably still my favorite but Maddaddam is a strong finish. 

If you like the end of the world type genre, this trilogy is top notch.