Yes, that's true! I think you might have put the nail on why I dislike book 4 -- it might be the one that has Harry alone the most. I mean, I like Harry, quite a lot. But I love so many characters, and the ensemblyness is one of the strongest points of the series.

I noticed also that the latter two books have a lot of scenes with Harry and Hermione and not Ron. I don't dislike Ron, but, well, I like Hermione and Harry and their friendship more. I do like Ron quite a bit more in Book 7, though.

And, yeah, Luna is so so good in all three books she's in. Stephen Fry's narration really does well by her, too.