This month's Issue 69 of 3D Artist has a great KeyShot 5 review by 3D 3D Artist, Jerod Bogh. Jerod had been beta testing KeyShot 5 along with the coming integration with ZBrush, so he's very familiar with the new features and helped greatly in making KeyShot 5 what it is with his feedback. Here's an excerpt from the review.
"KeyShot is really bringing the heat with its latest instalment. What should be immediately apparent to any experienced user is the new spring in every step. Large scenes load faster, shadows calculate quicker with more accuracy and it crunches through most renders at what feels to be twice the speed of the previous version... KeyShot 5 is a speed demon, which easily makes it a must have for any digital artist’s arsenal."
Definitely pick up a copy of this issue at your bookstore (or purchase online here) to read the full review.