As compared to simlab composer keyshot is userfriendly.
Keyshot has a fundamental difference with other rendering packages - namely the realtime aspect. Let's take an example: you apply a material to something in KeyShot and the same material to something in Simlab. In Simlab, you have no idea what this material will look like when it's rendered until you actually render it. In KeyShot, you see the results immediately and can tweak them in real time. Scale this problem up to an assembly with 50 parts. You are going to be doing a lot of intermediate renders (lots of time) to get your final result in Simlab. With KeyShot, you simply apply and you can immediately tell whether or not it's perfect - and you can adjust it in real time. The point of KeyShot is to make rendering substantially faster than in other packages.
Before KeyShot for Alibre existed (3 days ago?...) SimLab was turning out to be a good option for people because of the resolution limitations of KeyShot for CAD (800x450) and people did not want to spend $1000 to upgrade to a higher version of KeyShot. We realized this problem and worked with Luxion to bring KeyShot ($1000 version) to our customers for only $199, in general making the Simlab problem a non-issue moving forward.