I have had a set of these for just over 3 years now. They are on my primary keyboard. I'm a developer, have done all my typing on these keys. I love them. I'm a touch typist though, there is no legend on them. I have mostly white switches, with a couple browns for keys like backspace/caps lock etc, because with the white switches they bottom out and stay bottomed out (not the fault of these caps). I came from a fully brown keycap to white because I didn't like how the bump was not the actuation point (slightly further). Anyway these silicone caps feel soft and totally different than anything I've ever had and I've been computing since I was a kid (25 years or so). I originally had them on browns for about a year and they were great on that set too.
They seem to not be popular so its really hard to get your hands on them, to be safe I bought 2 sets to have a backup for the future. The wider caps like spacebar/shift/tab etc can be a little problematic at times but I switched to a split keyboard so my spacebars are now only as wide as the shift keys. People are complaining of these popping off. I've had that happen maybe 10 tens over 3 years, I don't know how people are that hard on their keys unless they are aggressively angry or something. They do build up finger scum heavily but they are so easy to pop off that cleaning them is actually easier than regular plastic keys. I just use my finger nail to scrape it off quickly - they are soft so scraping them is easier than harder keys since they have more give to break it up. They also do 'shine' over from constant use but what caps don't? maybe metal? So if you like the idea of soft keycaps, just get these, you can always have the longer keys have some other caps to alleviate the weirdness of silicone over long keys having too much wobble.
100% recommend these.