[GERGE]

Note: I am not here to give detailed lessons about typography, but I could give some book recommendations to those who want to learn why geometric typefaces are not good for body.

Type can be very personal. I would read with a slab serif if the book is published like that, but Inquite like ability to change them with ereaders.

But what you are saying here (I am speaking to you, JSWolf) is just your personal opinion. Typography is a science as much as it is an art and therefore there is some objective facts in it. But that Caecilia is a bad typeface to read is not one of them.

Let me explain.

Slab serifs (also called egyptian) like Caecilia are well suited to the body text objectively. Traditionally, egyptians are designed to draw attention; therefore they are advertisement and headline types; but recently some egyptians show a big design shift towards body-compatible shapes. Guardian Egyptian (type of The Guardian) is a very big example of this. Caecilia is also one of the important examples of this.

Caecilia is a body type, there is no way around that. It uses humanist shapes, large x-heights and counters. You might not prefer to read in it, I personally abhor it and would never use it, but both our personal tastes will not change the objective facts.

Also, what DuckieTigger said can also be considered in this terms. Sans-serif typefaces are not designed for body text. On pixelated screens, they can make full use of hinting and do not have fine details; therefore they are very good choices for web. But not for print and epaper (which is very similar to printing with new HD epapers).

Type is something immensely personal yet scientific. It is weird.

As last note, I use Kindle font files with my Kobo Glo, they render perfectly good. They are dark and legible.