“I’m Happy Just To Dance With You” was written specifically with George Harrison’s limited vocal range in mind and at a time when he lacked the confidence to compose his own material.
Lennon said that although he could have sung it- the song was written to give Harrison “a piece of the action.” On another occasion, he commented: "I would never have sung it myself.”
McCartney catagorized “I’m Happy Just To Dance With You” as a "formula song,” explaining in his autobiography:
“We wouldn't have actually wanted to sing it because it was a bit... The ones that pandered to the fans in truth were our least favorite songs but they were good. They were good for the time. The nice thing about it was to actually pull a song off on a slim little premise like that. A simple little idea. It was songwriting practice.”
Typical of an early Beatles song, the feel and storyline is very innocent with the speaker is happy just to be dancing with the girl he wants/loves. It has an old-time feeling to it of how a man feels when he is being smitten by a woman. In fact, it would have been found to be more suitable in an Irving Berlin or Cole Porter sound track than one of a rock/pop music group.
With its Bo Diddley rhythm guitar pattern and busy banjo style guitar playing in juxtaposition with Harrison's vocal, “I’m Happy Just To Dance With You” is unique as it begins not with a verse or chorus but with the last four bars of the bridge.
Beatle scholar Alan Pollack remarked:
“A brisk tempo combines here with relatively small section lengths to make this a short song with a paradoxically longish form; the refrain is not only repeated twice, but the latter half of it appears as part of the intro as well.”
Music witer Richie Unterberger refered to the track as a “strikingly catchy song with the kind of chord sequences almost nobody else in popular music was doing at the time.”
He says that is particularly true of the opening instrumental bars, with its haunting shifts between three declarative guitar chords. He says this opening is unconventional for rock songs as it begins with the last part of the bridge of the song, rather than going right into a verse.
Beatle scholar Terence O’Grady adds that “I’m Happy Just To Dance With You”exhibits a mixture of stylistic elements. He writes that it’s tempo is faster than usual for a ballad, and it begins in a rhythmically aggressive fashion with an introduction drawn from the bridge. The rhythmic accompaniment for the verse is a pseudo-Latin pattern generated mostly by lead guitar which is also exceptionally active for a ballad.