It's not bad, though for many people Mouse Without Borders is a better solution. You can get the installer from the Microsoft Garage -- microsoft[.]com/en-us/download/details.aspx?id=35460 -- but it runs constantly with Windows, which you might or might not mind [I do]. Or you can run it as part of PowerToys -- github[.]com/microsoft/PowerToys -- but that won't work for me as PowerToys is 64-bit only. Sharing the mouse, keyboard, and clipboard is handy for me once a month, on Update Tuesday, when I update & backup my 2 tablets, one of which is 32-bit. The light weight but less secure GiMeSpace KMShare looks like it might be a good substitute. Running it once a month it would be no big deal to keep it on a USB stick -- I'd guess it would be trivial for malware to fire it up, unless it's not on the hard disk :).
The app takes up <4MB, with a single file in Users\ [UserName]\ AppData\ Local\ GMS\. The registry gets 3 keys for the app, one for uninstall, while 2 rules are added to the firewall policies. The app has to be on both devices, which have to be on the same local network. You set up the connection using the IP addresses of each device. You can set it to automatically connect, assuming you set up static IP addresses for those devices in your Router's settings.