I really like these. The construction is certainly unique, though I would like to know how the PBT caps are bonded to the PC bodies of the keys. I'm somewhat concerned that they're glued which may deteriorate over time. I'm pretty impressed by what came in the box, though there's actually not enough keys to make an ISO layout - sure the big enter key is there and there's a \| key for the left, but there's no #~ key for the right side. Luckily there are several Page Up keys and one of those is R2, so that can stand in. A bit disappointing though. With any other set, I could maybe have matched a key from my stock of parts, but these keys are unique, so there's nothing that can stand in.
The thing that had me scratching my head though is the inclusion in the box of a spacebar stabiliser. What's that for? With the individual keys being heavier than usual, I wondered if perhaps the weight of the spacebar might be problematic. Certain the spacebar doesn't rebound as quickly as it does with a normal cap, but a stabiliser isn't going to help with that. I think I'll have to change the spring in the switch to be stronger - I'm using 50g matcha Akko switches and I'll likely stick a 100g spring in the spacebar. So what's the stabiliser for? Such a weird thing to include.
It's also worth mentioning that the PBT tops of the keys are smaller than the bodies on which they sit, so you lose a millimetre or two of surface area. But that's not a problem.
Overall though, I'm very pleased with these. The legends are nice and clear, the plastic is satisfyingly thick. The transparent sides do indeed let light shine through (not that I use the LED lights on my board). They have a pleasing feel to them and the more markings are interesting and fun. I don't know why the secondary markings are in Cyrillic, but it makes a nice change. Four out of five stars.