I got a Moonlander about 3 months ago, and it took me about a month of getting used to the key layout until I was typing at similar speed to a Macbook keyboard (which for me is fairly fast, about 120wpm). The hardest letters for me was shifting from my index finger to my ring finger for 'c', and shifting '.' from my other index finger to my other ring finger. I basically got used to never typing a key with my ring finger below the home row and with the ortholinear keys it was just no longer possible to type quickly while having my index finger handle everything. The keys also poke out quite a bit more than other keyboards so when you stretch to type a key with the "wrong" finger you are also much more likely to accidentally press another key.

Getting used to spacebar, backspace and enter, all of which I shifted to thumb mappings, took only a few days. You hit those keys so often you learn the muscle memory very quickly. This to me is by far the best part of the moonlander, having 4 super-accessible thumb keys and 2 semi-accessible thumb keys that I can program is a massive, massive improvement over a standard keyboard. Your thumb is completely wasted in a normal layout.

I still am far below my "normal" speed for programming, but that is because I'm trying to figure out the best custom mapping for (){}[]<>=+ and then train the muscle memory.

Overall I'm very happy with the purchase, I feel like it is much more ergonomic and with another few months of service and perfecting my layout it will hopefully end up being much faster and more convenient than a normal keyboard layout as well.