Finished the second of the 3 and taking a break before piling into the Stone Sky. I'm really impressed by it so far. I agree the narrative style is very unusual (at least for the sort of stuff I read). The overall story setup is excellent. I also like how the world building is explained as it goes and not explicitly basil expositioned at certain points. It feels very natural. Would also unreservedly recommend.
Just started The Arm of the Sphinx, directly after finishing Senlin Ascends, 100 pages or so in. Would absolutely recommend this too, my god it's amazing. The last time something totally blew me away like this was Cryptonomicon about 10 years ago I think. Obviously it may go to shit in books 2-4, but so far it's so so good.
While I'm here I feel duty bound to recommend Perdido Street Station and The Scar by China Mieville. Amazing world, and beautifully written. Two of my favourite books.
All of this with the caveat that I don't generally get on with the fantasy genre. LOTR bored me so badly I gave up. I've tried various fantasy books over the years and just cannot get on with them at all.