Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Best aliens in a long time!

Amazing! Human first contact with truly ALIEN aliens. Not hokey little green men or those stupid walking fetuses that are so popular these days. No way! The Moties are a work of absolute genius on Niven's part. They have their own solar sytem, described in vivid detail, their own complex evolutionary history (based on asymetry, rapid reproduction and extreme specialization) and a culture which is a logical outgrowth of their environment and genetic traits. Oh, and their civilization is VERY, very old. Human beings have been in space for 1000 years when this novel opens, but have not yet discovered other intelligent life. This fact alone makes me respect Niven. He doesn't create a bustling Star Trek cosmos where you bump into a new super-advanced alien every time you turn around. As if survival and civilization building were easy. He has a feel for the vastness of the universe---how unfriendly to life and civilization it can be.