VFDs and their backing LEDs look great and have a solid range of adjustable brightness (VFDs and LEDs) and color (LEDs only). VFDs are very easy to remove and replace (as far as just popping them off and back on again goes at least, don't have any spares to swap in) and their connectors feel sturdy (at least as sturdy as that sort of thing can be, definitely still be careful as such things are a bit delicate by their very nature).
Hard to tell from the pictures but only the smallest PCB (with the rotary control and backup battery) is connected to the base/stand with brass standoffs. The two bigger PCBs are supported only by the soldered pins between each board and the VFDs only by the connectors to the outermost board. It seems sturdy enough and is probably fine, but that does mean the (admittedly very little) weight of both bigger PCBs and the 4 VFDs is resting on the pins between the small PCB and the first large PCB. Like I said, it seems like it can handle the weight fine but only time will tell for sure. If its the sort of thing you are concerned about I wouldn't let it discourage you from buying this device, just plan on maybe adding some structural support yourself after you get it.
Basic out-of-box setup was easy enough to figure out (single rotary control on the back, click to cycle through settings, rotate to adjust selected setting), and the seller was very responsive and sent firmware files and documentation promptly when asked. That said, it would have been nice if some basic setup documentation was included in the box and/or if there was an easily accessible link to the digital documents and firmware files on the product listing or store page.
Related Note: What prompted me to contact the seller was to see if I could switch it from 24h format to 12h format, which it turns out isn't an option out of the box. Not a big deal and easy enough to fix if desired, but worth noting.
Haven't had a chance to hook it up to a PC to fiddle with programming it yet, but given the overall quality of the device and willingness of the seller to quickly send docs and firmware files I fully expect it will work as expected.
Shipping was prompt (ordered 2019/09/23, shipped 2019/09/24), but as it was international it was rather pricey and took quite some time to arrive (certainly not a mark against the seller, just something to keep in mind).
Overall very happy with this product.