Designed by a programmer, for programming. Named for its home position letters. Also known as Hallingstad's layout, for its inventor.
Pro Puts your thumbs to good use
Your strongest fingers are your thumbs. In this layout (unless you have a keyboard with thumb keys) you shift your hands up one row, and you use your thumbs on the bottom row. (Put your index fingers on QWERTY's
I keys, and rest your thumbs on VB and NM) The Ctrl and Shift modifier keys now use your strong thumbs instead of your weak pinkies. (Ctrl shortcuts are especially important for programmers.) The modifiers may contribute more to RSI than letters.
Con Hard to orient in a new position by feel
Most keyboards have bumps on two of the keys to orient touch-typists. On QWERTY, this is usually F and J, but sometimes D and K. On some keyboards you can fix this by swapping keycaps. You could also try adding small stickers with enough thickness.
Con Letter keys as modifiers may cause jamming or ghosting
Cheap keyboards designed for QWERTY might struggle with the use of Arensito's letter keys as modifiers. Gaming keyboards with n-key rollover don't have this problem. And any keyboard with proper thumb keys (Kinesis, Ergodox, Maltron) works properly. There is an older version of the layout that keeps QWERTY's home row that you can use on cheap keyboards, but it's not quite as nice.