This was a very well-done "first contact" story, in that it presented human contact with aliens from both sides. This in itself may not sound so original, but it is literally from both sides, as if there are two separate, parallel stories in one book. I love books that tell a familiar story from a different perspective (like Star Wars: Tales from the Mos Eisley Cantina or Zoe's Tale), but having both in the same book is even better.
Another original twist is that we (homo sapiens) are the "superior" space-faring species coming into contact with an alien race for the first time for both them and us. They, on the other hand, are at approximately the same technological level as pre-WWI human beings.
Lastly, the way the story is told is also unique: it is told as a narrative with conversations, as well as through a blog of sorts (called a "biolog").
So it is not just a first contact tale, but it is also a sort of "future history" and "alternate history" sci-fi book as well. As such, the characters and competing factions (in both species) are done rather well - in fact, the characterization of the "aliens" is done a little better than that of the "future human" characters.
For anyone who enjoys first contact stories, this is a must-read. However, if you like your sci-fi alien-free, this is not for you.