It's at least 80,000 words - about 160 pulp paperback pages. If you need more, Working Technologies also have special super-capacity models with one or four million keystroke memories. Decoding some stuff from a KeyGhost log dump is like reassembling shredded documents. Overall The KeyGhost is a powerful snooping tool. Like most powerful snooping tools, it can be used to do good things, and bad things.
Key loggers are a dead easy way to make an end run around password-protected systems.
And a hardware-based key logger like the KeyGhost means you just need a few seconds to plug the thing in. Connect it, come back later and retrieve it, plug it into whatever other computer you want at your leisure, dump the log to a file, and search for the username. Again, there are people who have a legitimate use for gadgets with such capabilities - criminal investigators, chiefly. It's likely to be a lot less useful for programmers, since all of the hopping around involved in coding means that decoding a simple serial keystroke dump is likely to be a great deal harder than just writing the code again. Frankly, the more I think about the legal and ethical issues surrounding gadgets like this, the harder I find it to figure out whether they're a good thing or not.