On the secondary PC (the primary is the one with the controlling mouse and keyboard), the mouse motion may appear slightly jerky. But keyboard typing shows up right away on both monitors, and without any noticeable delays or skips.
Multiplicity runs as a service on each PC, and upon first being installed it will prompt you to tell it whether it's running on a primary or secondary PC. It will automatically search for other Multiplicity-enabled PCs on your home network, but that search was unable to find the secondary PC in our network. It did work fine once we manually provided the secondary's IP address.
The regular version of the software allows for copying text between the two controlled computers. You can control up to six secondary PCs with the $50 Pro version, and also copy files and folders.
Multiplicity doesn't allow remote desktop access like software such as GoToMyPC, but instead is meant for when you want to easily manage multiple PCs that are in the same place.