This is by far, the best Echo / system we have owned from Amazon.
We purchased 2 of the generation 3 Echos and an Amazon sub as a package (saved $80 + an additional $60 for taking the Amazon store card) to replace the Bose speaker / Echo Dot we had.
We now have room filling sound as good as the Bose combo without having to physically turn on the speaker every time we wanted music.
Even without the sub, the sound is robust and rich from each of the linked speakers. The addition of the powered Echo sub fills in the lows to make it an immersive experience.
Setup was fairly easy. My only complaint was that I had trouble renaming the 2nd Echo itself. Amazon keeps calling it another wacky name. Overall, it took less than 5 minutes to link all 3 speakers together and be listening.