Thanks to
@amirm for testing this fun device!
First, regarding the app. I suspect amirm has a wifi system with similarities to mine, which employs three separate bands (2.4 plus 2X5 MHz). I had no problems with my Android devices but couldn't get my Surface tablet to connect with the Node. Turns out my Ethernet connection in my office connected to the wrong "band" (the wired connection was network band MaxBuckOffice, while the wifi that the Node connects to is MaxBuckHome). So everyone who has multiband wifi systems (or who is connecting using Ethernet hard wire) needs to make sure they're on the same network band for both the Node and whatever control device they use to run the app.
Second, I regard this device as presenting massive value. I am not a hobbyist, and have no interest in assembling Pi devices of any flavor. I'm interested in plugging and playing, which this thing has done flawlessly without requiring me to add a monthly Roon subscription to access streaming music.
Third, I'm still on the fence on the DAC. It's good to know that its performance is at best marginal, but that's easily remedied by employing an external DAC. And I have to say that in my (non-ABX) comparisons playing direct and through a Modi 3+ DAC, I don't hear improvement bypassing the internal DAC. But I don't pretend that my hearing or listening skills are very good, and my house is quite noisy.* So bottom line is that it serves my listening needs exceptionally well.
As for whether the app is useful or frustrating, like most UI issues that's a matter of personal preference. Personally I find it to be excellent, but others obviously think different.
*We have an interior water feature that flows pretty much all the time. And our A/C here in SoCal has also been running pretty much full-time, and the equipment is roof mounted near our listening room. So until the winter when it won't run much, things won't improve. Our noise floor in our home is about 72 dBA right now, according to the SPL app on my phone.