(Disclaimer: English is my second language, so I want to apologize in advance for there may be mistakes in the text below. If you find any, please let me know so that I can correct it. I'd really appreciate it. Thanks.)
I didn't really know what to expect from Aurora, Kim Stanley Robinson's new novel. 2312 (my review in Spanish) had a lot of wonderful ideas and many amazing images, but, in my humble opinion, had a very thin plot, two-dimensional characters and, worst of all, was really boring. Aurora approaches some of the same topics (in fact, they seem to be set in the same universe although they are completely independent) and is, all in all, a much better novel though with some issues of its own.
Aurora is, mainly, a generational ship story and the reader will find in it most of the tropes of the subgenre, with special emphasis on the sociological and technical problems of such a long voyage. In fact, the first half of the novel is quite conventional. Although it is very readable and I found myself having read a good chunk of the book without almost having noticed it, there was nothing especially compelling, nothing to make Aurora stand out from the dozens of generational ship stories out there.
The second part of the book, however, is much better. After a certain event that I won't mention to avoid spoilers (and with which I think the author cheated a little bit), the story becomes more interesting and much more original. There are some really amazing scenes, full of tension and sense of wonder, that are, hands down, the best part of the novel and will really appeal to fans of hard SF. Also, the ending has some unexpected (at least for me) connections with a certain novel by Stanislaw Lem (whose title, again, won't mention for it would spoil some surprises).
Together with these brilliant parts, the novel also shows some problems. Although the story is much more focused than it was in 2312, the exposition comes mainly in the form of big infodumps, something that might be annoying for some readers. In this case, this style is justified to a certain extent by the choice of narrator, the AI of the generational ship, that in fact is trying to learn how to tell a story while recounting the travel to Aurora. This could explain some clumsy parts and the continuous use of long explanatory fragments, were it not because it also aligns nicely with Robinson's usual style. If this in intentional or just unavoidable is something that will be left for each reader to judge.
All in all, Aurora has left me with mixed feelings. I don't regret (at all!) having read it and, in fact, I will certainly recommend it if you feel like reading a generational ship story (especially for the second half of the novel). Also, it made forget my disappointment with 2312, for Aurora is much better in almost every respect. However, I must say that I've read quite a number of better SF novels this year (Dark Intelligence, Children of Time, A Prospect of War and The Water Knife, to name a few) and I dare to say that you can safely miss this one if the topic doesn't appeal that much to you.
(You can also read this review in Spanish/También puedes leer esta reseña en español)