As good as "From Me To You" is, it becomes pretty much a footnote to history between "Please Please Me" and "She Loves You." It's a splendid example of the Beatles "formula," whatever that is, that combination of personal pronouns, harmonic vocals, and "oohs." "From Me To You" was just a slight upgrade from the previous single, to prove it could be done again. It's kind of a masterclass in "How To Write For An Audience," an undervalued skill in rock criticism. They were trying to write for their listeners, and they were trying to write stuff they'd enjoy playing, at a time before it was certain that people would love Beatles songs no matter what they ended up doing.
I once read a not-terribly-good Beatles book that pointed to "She Loves You" as a moment of early complexity, because of its third-person narrative. I think that's overstating it a bit: from what I can tell, it's more of a case of "We've written three singles and b-sides, and most of an album, of songs saying I love you. Let's change it up just a hair." To praise "She Loves You" for its lyrical themes is like praising the Grand Canyon for its color. Yes, it's there, but isn't that sumbitch huge???
"She Loves You" is an important moment, though, because it's an excellent song, and shows the Beatles' dedication to topping themselves. For me, it isn't that "She loves you," it's "Yeah, yeah, yeah!" They add so much energy and urgency to the proceedings, as does the thundering roll of Ringo's drums. This song, more than most early Beatles tunes, is an inseparable blend of form and content. It just has to be delivered fast and loud. This was the sign that the Beatles were creating something great, not just emulating.