I saw a typing game and, being someone disproportionately proud of her typing skills, immediately could not turn down the challenge. Verdict: it just seems like a normal typing speed exercise, but with the added challenge of sometimes wrong letters happen at random for no reason, and if you're going fast enough (like I was), you only register that it happened after you've submitted the word and there's no time to question what happened or why. Fits the theme well, but it's not enjoyable.
That being said, Classic mode is an utter delight. I'm probably going to use it as a warm-up for writing sessions for the forseeable future. <3