Earth Unaware was not as good as Ender's Game or Ender's Shadow, but it's definitely up there with Speaker for the Dead and Shadow of the Hegemon.

The one issue I had with it was that it seemed like it changed the canon from the original book: Ender's Game was not set in a 21st century vision of the future, as you can see from the references to tension between the US and Russia, and the lack of any sort of portable computing technology. The impression I got from the original book was that the original Bugger (or Formic, or whatever they're calling them now) invasion took place at the end of Cold War, and humanity barely fought off the invaders with the technology that they had then, and, by the second invasion, had reverse-engineered Bugger technology to the point that they were able to build space ships, ansibles and so on. This is obviously not the case in Earth Unaware, but that's a small grievance about what's generally a pretty good book.