Overall I still think it was the weakest book due to some weird pacing and the overall theme not being as strong as the others, but it still held its own and had a lot of memorable and good moments. I don't think it comes as any surprise or even spoiler I thought the ending was pretty great, it's a Sanderson book after all.
I didn't make the Kelsier connection til I read the spoilers in this topic and wow I can't believe I missed that. That is certainly a reveal all right. And Taravangian becoming Odium is an extremely interesting turn I didn't see coming. It almost feels like this was the 'halfway point' in the series where we have a big turn and go into something greater scope, if we didn't already have a clear indication from Sanderson that book 5 is going to be that.
As far as the actual tower conflict, it was definitely the weakest of the finales across the books IMO. Teft dying and Kaladin swearing the fourth ideal was pretty emotional, as well as Navani becoming a Bondsmith, but it didn't quite have the punch that I have come to expect from the series so far. Still good, and man Raboniel was a great character. Easily one of the most interesting characters in the book. Also I am fully on the 'screw Moash' train now.
I think the bit I appreciate the most from the ending though is that Sanderson gave Eshonai a nice send off. She was one of the most tragic characters in the series and deserved far better than she got, and its nice to see she at least got to live her dream at the end.
I think having just reread them I'd rank the books 2 > 3 > 1 > 4, but there's not really a big quality gap between any of them.