In reality, the reviews on Amazon.com tell us more about the reviewers and the review process, than about the book. It seems that most of the reviews written on Amazon.com (and other sites), are penned by those who either cheerlead for a product, or those who revile it. Very few reviews are written that place a product solidly in the middle of its category. That is, the product is neither awful nor wonderful, but rather, it is serviceable.
That is the case with McDevitt's Omega. The book is none too deep, nor is it too challenging. The science is certainly less than complex. The characters are generally believable, but I could never shake the impression that they were somewhat shallow character sketches.
Having said all of that, I did finish the book, and did generally enjoy it.