I'm using the Swype keyboard for months now and I'm very happy that I bought it.
It appears fast when I need it, the layout is perfect and I stand amazed with its predictions (it seems to know exactly what is the next word I want to write). The more I use it, the more it improves itself, since it learns the words I write.
It's pretty easy to start using it. After the initial installation, you need to download one (or more) language packs (with the words of the language you chose). The configuration screen explains itself.