As much as I appreciate the tiny serif for lowercase L and numeral 1 to differentiate l I and 1, I am not the biggest fan of the capital I glyph without the horizontal serifs. It's my biggest design gripe with most sans-serif fonts as it makes it FRUSTRATINGLY difficult to differentiate when looking at words by themselves. Is that lota or Iota? Is that iodestone or lodestone? Both real examples where I fumbled readin…
When I had to make a decision about should the Google results pages be serif or sans-serif, I didn't have enough users to do the split A/B testing and mathematically figure that out, so I ended up reading a lot of research and ultimately finding out that serif fonts are more readable, and sans-serif fonts are more legible.
The serifs create a horizontal rule that guides the eye, so serif fonts are much better when you’re reading long pieces of text. Sans-serif fonts are more legible which means that... when the serifs are removed your eye can spot read a character much better and much more quickly, and as a result it is much better for spot reading. In an activity like search it turns out you want to facilitate spot reading to a much greater degree than reading long prose.
Here's the 2006 talk: https://stvp.stanford.edu/podcasts/nine-lessons-learned-abou...