I don't own them, but I've had a good listen.
They are very good.
Bugs and software issues. It seems from reading the Devialetchat forum, that various issues come and go with each software update. Some haven't gone away.
Some people have received faulty Phantoms that have a low but audible hiss when no music is playing. Replacements are issued.
There are no coax inputs. Only one optical and one Ethernet on each Phantom.
If running two as a stereo pair, where you must use the Dialog box, there is only one input each of Ethernet, USB and optical on the Dialog.
Control (including volume control) is carried out via the Spark app, which has its own software issues, in so far as being widely regarded as a work in progress, or under featured at this stage of its existence.
They say it's gradually getting better with each update.
An optional stand alone volume control remote is now available, but it falls well short of what was promised and can only adjust volume and does nothing else (no promised e-paper display, no play/pause/next etc,). At £129 too!
Spark handles the streaming aspect, such as the integrated Tidal, Qobuz and Deezer services, as well as streaming from a local network source.
Some people have problems with using Spark for streaming, or just don't like it in its current form and use their own streamer (Sonos etc,) plugged into the Dialog's optical input.
The matching Branch stands, which were originally thought to cost £199, have turned out to cost £299 each.
They weren't available at launch, with only a small batch becoming available several months later, only to go "out of stock" again. Next availability Xmas or early next year? Who knows?
Having read a lot of user reviews and posts on the chat forum and elsewhere, my impression is that the sound quality is considered to be very good and if set up correctly will match or completely outgun many if not most component and speaker setups costing up to many thousands of £'s.
The biggest fans of the Phantom, appear to be the owners of very expensive main systems, costing serious money.
There are the usual issues regarding placement, especially so with the prodigious bass levels and they are reported to take a while for the drivers to loosen up and bed in, with a consequent improvement all round in sound quality.
The Phantoms are clearly not without technical issues and many of their owners appear to be getting a little bit frustrated.
The accusation or impression is that Devialet are slow and under resourced in the software development dept. and are very poor at communicating the progress being made with fixing issues and with new developments.
My own impression is that they have a technically brilliant product, that sounds exceptionally good, but is being held back by underdeveloped software and a slow response to dealing with problems.