My Review of the Sonos Play:3 speakers

Now that I've had the Play:3 up and running for 48 hours here's my take on the newest entry into the Sonos System.
The Play:3 appears to be Sonos' foray into a speaker system for the smaller room/area. In my case it's in our master bedroom which is a 10x12 space.
The setup was painless, as usual, and the speaker was up and running within minutes.
Sound: I ran my usual 'test mix' of music ranging from rock through classical (I've never found anything better than Dvorak's New World Symphony, the Von Karajan version, to test speaker ranges) and a radio station to check voice reproduction. As expected for a unit of this size the bass was a little lacking and faded out the further you got from the unit but the rest of the range was bright and clear. All parts of the sound improved when I put the speaker on a table in the corner of the room and allowed the sound to bounce off the walls (I faced it out but it still helped).
More interesting, and problematic, to me were the choices Sonos made on what to add and leave out of this unit.
1) There is the addition of a mounting hole on the back (check the photo below) for attaching to a bracket (Not included & currently Sonos does not offer).

At 10 pounds the speaker will require firm attachment to remain secure but the depth of the hole seems to be deep enough to provide for this.
The problem is the placement of the mounting hole. Although the unit can be placed vertically and the speakers adapt (confirmed by my testing) this only works with the right side down, not the left. For some reason Sonos placed the screw hole to the side of the unit instead of squarely in the back. This means that any mounting bracket will have to supply a 'shelf' as part of it's structure or clamp around the sides of the unit to prevent levering and potential damage to either the unit or wall since if simply screwed into a stud the weight will be carried at the lower part of the unit (if mounted vertically) or off to the side (if horizontal). Perhaps this choice was dictated by the interior design (I didn't open the unit to check) but it was, IMO, a poor choice a center place mounting hole would have been better.
Also the power socket and Ethernet port jack are close to the mounting hole. This means either running the wiring through the wall or having to mount at least 2 inches away from the wall for adequate clearance for the power cords (this may have been intentional since they recommend a minimum of 1" of clearance around the unit for ventilation and that will place even further leverage on a single screw mount).
2) What was left out as opposed to the S5/Play:5 unit:
A) There is no Ethernet out jack on the back so you have to use a separate port from your router to connect this if it's the first component.
B) There is no line in jack. In my case it's an issue since I was going to add a second Bluetooth receiver and continue to stream audiobooks from my phone to the player as I do with the S5 in the kitchen. I know that I can add a wireless bridge for iPhones but I have an Android phone and that's not possible since the wireless bridge is iPhone/iPod only. The lack of an line in jack means leaving my phone in the kitchen to stream the book in the bedroom, a nonstarter if I need to use the phone. Also, I was considering giving a Play:3 to my son for his college apartment & using Bluetooth to stream from his iPhone. The price differential of $30 for a Bluetooth adapter vs $120 for the dock is a nonstarter as far as I'm concerned.
C) There is no headphone jack on the back meaning that, unlike the S5/Play:5 you can't listen privately through the system

Conclusions:
The Play:3 is an interesting option for the smaller room if you already own a Sonos system with more than adequate sound quality for speakers of it's size but it's lack of input/output ports on the back make it 'iffy' if you're going to use it as your only speaker for the system.