I'm just over halfway.
Still enjoying, which is just as well; if I'd been expecting to remember this book from my childhood then it'd be a washout. The dialogue style is very Lewis; it seems weird coming out of a child's [Caspian's meant to be about 12 here, isn't he?] mouth, but I rationalise it as it being like the TARDIS' ability to translate languages.
Just because the Narnians sound English, what's to say they're speaking it?