Proxima bills itself as a planetary romance with exploration and colonization of an alien world. The book certainly has plenty of that, but it also has two other subplots: a political one involving a Cold War-style detente between the U.N. and China, and a cosmic mystery with consequences to the universe, and possibly the multiverse, at large.
The planetary romance aspect is decent and interesting, even if the world feels a tad underdeveloped. It was my favorite part of the book. However, because of the other sub-plots, there wasn't as much as I would liked and by the end that side of the book was overshadowed by the politics and mystery.
The politics itself was fine, but there were some lingering plot-holes and background that never got explained. I wasn't expecting the mystery sub-plot at all. Individually, the sub-plots are fine, but altogether they don't really fit quite right. This book is also clearly the start of a series, yet there is no indication of that anywhere until you finish it. I strongly feel that the marketing completely failed to convey an accurate sense of the book.
Finally, there's also the fact that every single character was dull and annoying. I'll give this book three stars because I know there are people who will enjoy it, but ultimately it's forgettable.