Most important add-on to any Org.
We have advised 100's of clients and implemented more than 75 salesforce org's from scratch over the past 20 years. Without a doubt, this is the best App you can add to your org. Support is incredible - these guys are PROUD of their product! - and you can find help online by searching for just about anything you want to do. And the best thing is...they add features almost as intuitively as you think "it would be great if this was possible."
Cannot be a big enough supporter - just get this if you need to have any data interaction with someone outside the organization or need better features and visuals than you can get with Page Layout.