I use VNC quite heavily. In the office here, I work on a WinXP machine (not my choice…), and always have at least one VNC session open to the local server, ls1 (“Linux Server 1” – not imaginative, I know 😉 ). I sometimes connect to a local MacOSX box as well, when I’m trying to get something to work in Safari.
The biggest problem I have, though, is when I access my home machine, Monolith. The screen refreshes take about 10 seconds to complete through VNC!
There is an improved server/client protocal out there, though – the NX protocol. It is incredible how much improvement there is, when I connect to my home machine with it!
To try it out yourself, either grab a copy of the FreeNX package and build it yourself, or if you’re using Fedora, follow this list of instructions (which, handily, you can just paste into a tmp file and run as a script).