"The Mote in God's Eye" by Larry Niven & Jerry Pournelle.
Most striking thing about it so far is how closely a lot of the background/setup to the book parallels the BattleTech setting: The year is 3017 (vs. 3025), humanity is recovering from the Secession Wars (Succession Wars), there is a hereditary nobility, there's a planet filled with people who speak in phonetic Scots despite living 1,000 years in the future (Skye/Nortwind), interstellar travel is accomplished by Alderson Drives that allow ships to jump from point to point, though these points must be far away from stars or large planets.
The actual writing/story is a bit pedestrian by comparison. The verra nae ken we noo Scots engineer is an irritating stereotype, and the main character is so dull he could be played by Sam Worthington. Still early going yet, it may pick up.