A few days ago, the highly anticipated GravityForms plugin launched to the public with much fanfare. However, many people voiced their concern that there was no way to try before you buy which put off a lot of folks from buying it. Thankfully, the RocketGenius team is a responseful bunch as they have launched a specific DEMO site where you can login to the backend to see the plugin in action, create new forms and see how it all comes together.
One word of note though is that some of the settings for the plugin have been disabled such as saving new forms, deleting forms, etc. However, you should be able to get a good feel on whether the plugin will fit the bill or not.