In short they are ideal. Not many technology people have any idea about information, so you need to be very clear about what you are trying to achieve - otherwise you will have the wrong design and you will waste some of your money. An Intranet is an internal network built on the same technology as the Internet Web. They can also be run over the Internet itself, which is cheaper, but less controllable. That is a key decision to make.
People find using the Internet interesting, fun and easy.
So they use it. When you are tying to sell knowledge that is an important component. Above all else this is the real attractiveness of the Net and a selling point. A legal firm would use an Intranet for knowledge access using legal databases and document distribution, such as precedents. Using an Intranet for commerce - such as conveyancing processing and processes like filling in internal forms could be considered at a later stage.