I bought a Zolo Halo on sale at Amazon for $40. After using it for a day, I bought two more, so I now have 3 Halo devices throughout my house. Now that I've had these devices for about a month, I figured I would finally post my review!
Overall rating: 3.5/5.
I like these things. They're powerful little speakers that handle anything I could want in the house I'm renting right now. FWIW, I have about 1000 sq. ft. spread out over two bedrooms, a sunroom, living and dining room. I currently have the Halos in the living room, the bathroom, and a "portable" one that's on an extension cord long enough that I can move it for use in the bedroom, sunroom (study), and dining room.
I love being able to link them so that I can have coordinated music throughout the house. It's great for parties, and keeps me from having to blast the volume in one room so that you can have background music in other rooms.
I've dropped the rating from 5 for a handful of minor reasons. Only one of these is enough to really drop the rating by itself, but there are so many little things that they do eventually add up.
The microphone on these things is weird. I like to listen to flash briefing at breakfast, so I'll bring the "portable" Halo into the dining room and set it up about 5 feet away from me (without anything around it to interfere with the pickup). When I ask it to play my flash briefing, the unit 5 feet away from me won't register anything I say, but the unit 30' away from me and the unit behind a closed door in the bathroom will both start my flash briefing. It gets frustrating having to remember to hit the button to stop Alexa from listening every time I leave a room and to turn that off every time I enter.
This one goes with the above point. You can't change the wake word for the device. If I could do that, I would simply have each device answer to a different wake word.
Lack of ability to transfer audio from one room to another. Sure you can link it, but if I'm leaving one room, I don't want to play music for an audience that isn't there. Subpoint: there isn't a voice command that I've figured out for linking units.
No support for iTunes: I'd love to transfer my playlists to the Halo, but you have to do this one song at a time. The playlists I create are huge, so I don't want to add songs one at a time.
This is a big one for me: No voice support for Spotify. If I want to listen to music from Spotify, I have to start Spotify on my phone and tell it to play from a particular Halo. I like my music loud with some decent clarity, but this alone is enough to give me some buyer's remorse. I pay the fee for Spotify because I like it so much more that Amazon's music service.
No drop in feature.
In summary, if I could go back and do it again, I absolutely would still consider buying the Halo. In the end though, I do think the lack of voice commands for Spotify would be enough of a con to push the smaller speaker on the Echo Dot above the Halo. With that said, if I had enough house (and back yard) to warrant more than a couple devices, I would definitely purchase a handful fo these to use as a secondary device, mostly for synchronized music at parties.