As for "The Last Battle" specifically, I enjoyed this one, but it was probably my least favourite of the series. The main part of the story was interesting, although I found that it stretched even my great capacity to suspend disbelief. Hmnh. I think from here on out, this will be spoilerish, so consider yourself warned . . .
Would the talking animals *really* have gone along with the "new" Aslan - or the concept of Tashlan - selling them into slavery, etc? My instinct says no - then again, I can look at what people in this country today are buying into from our own corrupt government, and perhaps it's actually NOT outlandish after all. Oh, that's a sad, sad thought, isn't it? I did, however, enjoy what happened in the stable towards the end - how each person who entered saw something different (or one of a range of things) which corresponded to his/her own experience/behaviour and expectation.
Perhaps one of my problems with this book was that I found it the most overtly allegorical of Christianity, in a way that doesn't "speak" to me. Jesus vs. the Devil (Aslan vs. Tash) is not part of my own religious view. That's not necessarily a problem for me when reading fiction, but for some reason, in this particular book it seemed over-the-top and too obvious, and annoyed me just a bit. I got the feeling I was being preached at, something I don't enjoy. I also found the last section of the book overly long and tedious - all the stuff about swimming up the waterfall, etc. Yeah, I GET it, Aslan's country ROX, now can we wrap this up already? :D I couldn't help but thinking that we'd already seen something similar at the end of "Dawn Treader," but it was so much lovelier in that book. (Admittedly, not exactly the same, but I found the two sections very similar). Although I did enjoy seeing Reepicheep again (I <3 that mouse). I do wish Lucy had encountered that mermaid shepherdess again in the "real" Narnia, though. :)
The things mentioned above, though, are of less importance than my feelings about the very ending. Maybe I'll feel differently in time, or after a subsequent reading, but I'm just not sure I found it satisfying. I hadn't guessed about the train wreck (although in looking back, yes, it was most assuredly foreshadowed). But argh! While I love the idea of the Pevensies (especially Lucy) getting to stay with their beloved Aslan, OMG, they were so young, and it just seemed so sudden and violent and somehow gratuitous. It made it a bit easier to know their parents were there with them (not Susan, though, something which I found sad, but not surprising. I had a hard time warming up to her throughout the entire series, although I was surprised to see her slammed quite so hard in the final book - what happened to "Once a Queen in Narnia . . . ? I guess Lewis needed to make the point that not everyone gets to go to the "good" place, but I thought it was pretty harsh). What about Jill's and Eustace's families? And does Lucy, now, never get to grow up? Oh, I guess we're not supposed to think about that, but I found it really shocking, and sort of an uncomfortable way to end what was otherwise a fanciful and very charming series of books.
I guess Lewis wanted to make the point that Heaven is the real destination, and the only one that matters, but yow. I felt a bit battered by it, when all is said and done. Perhaps it's just that his vision doesn't conform to my own, but I found myself feeling sad at the end of things, rather than uplifted.
After saying all that, I suppose it might be surprising that I'm rating the book 7/10 - but I really did enjoy it. Well, most of it, anyway. And I was glad to see the Pevensies in this book - I missed them in the books in which they did not appear at all. Especially my darling Lucy. 7/10.