Turning that off makes gaming better.
Not just games, either! I use the ‘vim’ editor quite a bit; every letter key has a command associated, and several of them are for navigation/searching/&c where being able to autorepeat is vital. I had to turn off the press-and-hold variations almost immediately.
Which is a shame, as there's no other easy way to enter non-standard characters…
The Psion S5 had several standard shortcuts, e.g. Fn+Z would add an umlaut to the next letter, Fn+X would add a grave accent, and so on; you could also hold down Ctrl and type a decimal character code. macOS has some handy Alt+ shortcuts, too.
But on the Gemini, the only other methods I know of are pressing Fn+, to show the on-screen keyboard, switching to the relevant page, and holding down the relevant character (which supports only a limited subset of characters) or opening a text file with all characters and copy-and-pasting the one you want (which is extremely unwieldy).
It would be really good if there were easier ways to enter accented letters, long dashes, curly quotes, non-breaking spaces, fractions, chevrons, sub/superscripts, ellipses, arrows, &c!