I would say the layout is easy to adapt to, but that is subjective. I was pleasantly surprised how easily my right pinky got used to going a little farther to hit the tiny backspace key, although it took a bit longer for it to hit the ISO style Enter key consistently. I plugged it into my Macs, so like any new keyboard plugged into a Mac, it does its little detection scheme. It wanted to categorize it as JIS, but I selected ANSI and it treated it like it an ANSI board. I put ANSI key caps on it, so that helped me. One thing that bugged me was that different programs would read keystrokes differently, like email would read fn+bs as del, but other programs wouldn't and it would just be bs whether I pressed fn or not. That was annoying.
But typing on it was a real pleasure, what a great implementation of Topre 45g. I sure would love a nice ANSI 104 key Type-S keyboard from PFU built like the HHKB Pro 2 with PCB mounted Topre switches.