First, simply as a keyboard, it is good. The feeling is pleasant and solid. Of course, will take time to get used to it. The symbols on the keys are a bit weird, but funny. And I usually type without looking at the keyboard anyway.
Overall, the mechanical quality and build is good. I do not know what do others complain about, just a simple and minimalistic thing. Who needs function keys? You have Fn+digit. On the real kb with the function keys I almost never used them anyway - they are too far.
I have two major concerns about it.
First, complete absence of useful documentation. The little booklet is what you get. This is an engineering product, it is supposed to be for the geeks who know how the keyboards work. Where are the specs? Any technical documentation? Nothing. OK, I have got original Via working finally with that JSON file they provide - although it is an old file and it does not even completely match the keyboard - it looks different. But, at the end, I was able to program a few extra keys. You have to remove the keyboard definition and add it again every time you use Via, otherwise it won't find the keyboard. And, no, I won't be using any binaries from any untrusted sources, only the open-source products that I can trust.
Next, the little screen. It is totally useless. Again, given the lack of documentation and the tools for Linux to manipulate it, it is useless. Who would know that the strange "Image Update Tool" (by the way, I would not dare to use it for the images, because there is no documentation) is what you need to update the date/time?? Of course, again, a very suspicious binary with missing Windows dependencies - I would never install it on a real system. Luckily, installing it in a discardable offline Windows VM works fine.
Finally, not really the keyboard's problem, but still - I bought the matching silicon pad and while it is quite comfortable, it slides too easily. It needs to have some rubber at the bottom to stay in place.
Overall, for the price, I think it is a good product. The main concern is that it must be more open on the engineering side to satisfy the people buying such things.