Count me as one who thought "immersion reading" was a gimmick I might use on rare occasions but no more than that. After using it for a couple of books (Moby Dick, From Here to Eternity), I'm hooked. And I'm not even sure why.
Perhaps it's the reinforced focus of hearing the book read while I read it, a feature that's especially enjoyable with Melville's dense prose. I certainly don't feel it's essential. Been reading long enough that I have a voice in my head that works quite well. But I'd be lying if I said I don't enjoy it.