Summary: I'm a network admin for 16 years and this is so easy to get working a second grader could do it. If you need to connect multiple machines to one keyboard/mouse/video, this is for you. Price is very reasonable. I've seen similar products for over $200.
Summary: Works well if you need to work on four computers at the same time with only one mouse, monitor and keyboard. Good device if you have to repair or troubleshoot many computers at one time or to use on gaming computers to switch between computers. Works well if all computers video outputs that use VGA ports. If you need DVI ports, Trendnet also makes KVMs for DVI as well should you need it.
Pros: 4 computers can connect to this, sharing a keyboard and a mice, instead of 4 of each. Works a great deal of the time (see cons). It has buttons to make it easy to switch, though the hot keys aren't too hard to remember either. Comes with useful cables.
Cons: It Works Most of the Time, though when it doesn't, it can be a pain. It typically doesn't work when you switch from a computer and back, it would take a few minutes for the other system to be up and about. USB 1.1 compliant, I honestly thought this was a USB 2.0 console, so only share keyboard and mice here, or get a cheap USB hub if you have a drawing tablet you use on all your systems.
Summary: Usually, this error is benign (if annoying). But I have also experienced, as others have reported, situations requiring a complete shutdown, where the unit fails to be recognized — again, only on Linux (Debian 6.0.0 with kernel 2.6.32-5).
Pros: No separate power supply, although this is arguably a con (see other thoughts). Same with cheap.
Cons: Although the product is advertised as working with Linux, there are known, unresolved issues (just search for "couldn't find an input interrupt endpoint") that affect usage with various Linux distros.
Cons: Technical support does not exist. Was having problems at the begining (due to VMWare, details below). Tried to call their support number and was putting on hold forever; Send email to their support box and never heard anything back