The Point-of-View of The Silver Chair is unusual for a couple of reasons. Like most of the series, it is the perspective of childlike wonder at a new world. Unlike the books following the Pevensies, the children having an adventure are not siblings. They reach Narnia by very strange means (arriving in Aslan’s country and then being blown there). But the main thing is in terms of which protagonist is (mostly) followed.
All the books (so far, at least) have been focused on 2-4 children transported to a magical world. Only in Voyage Of The Dawn Treader has there been a difference in experience between the children (in terms of having been to Narnia before). There, Eustace was the newbie, but things were still told from the perspective of Lucy (a veteran on her third trip). This time, however, though Eustace is returning to Narnia, the story is still told from the perspective of first-timer Jill Pole*.
Like Magician’s Nephew and Horse And His Boy, though, the non-sibling male and female pairing do tend to rub each other up the wrong way, even though they’re actually very alike. After all, we can’t show boys and girls getting on well together – they might catch something!
* As an aside, it’s interesting to note that – apart from Horse And His Boy – the viewpoint character is female.