It's Worth It. With OmniGraffle 4 good things just keep getting better
Caution: This is based on a product version still in development, so while all these features should be in the final release, and I have attempted to make sure that everything written here is accurate, don't hold me to it. You want a guarantee? Buy a toaster.
OmniGraffle has gained a few features along the way. One of the cool things that it picked up in version 3 was the ability to make multiple canvasses in a document and then run them as a slideshow presentation. It isn't as flashy as Keynote, but the pages, with brainstorming sessions, family trees, phone and decision trees, and tables communicate a lot more than is easy to do in Keynote.
Notes are also new. They make sense coming from OmniOutliner or most presentation applications, where you make notes to elaborate on points in the outline, or slides in the presentation. Here, the note appears as a small note icon overlayed on the stencil object in the canvas, and as a overlay similar to a tooltip or html IMG ALT tag in presentation mode, where the note hovers above the object.
Tables are something that word processor, diagramming, and presentation applications have tried for years to get right. Some applications use wizards, others use menus, or buttons. Here, OmniGroup gets it almost right: Command-Shift-T makes a table. Dragging the handles of the table horizontally or vertically adds columns or rows to the table. This can also be done from the Edit -> Tables menu.
There is now a setting for ruler scale. This means that it is possible to set the condition that 1cm in the document is equal to 1m in the real world, for example. This comes in handy if you're making a diagram that is meant to be to scale. I admit that I have a hard time imagining when this would be absolutely necessary, unless you're laying out furniture in a room, but it could make sense for some types of wiring diagrams or for maps. OmniGraffle does include a map of the United States of America.
If you're like me, many of the diagrams you make require a lot of the same objects, with lines connecting all of them. If you select an object in the canvas, command-click and empty part of the canvas. Then command-option-click. It will create the object with links between the original object and new object. Create as many child objects as you please. This speeds up creation of a wide range of documents.
Version 2 of Omnigraffle added automatic layout. Version 3 gave us diagram styles for the automatic layout. New for version 4, we have more diagram styles at our disposal (basic, business, brainstorming, glass, neapolitan, text) and it seems to handle automatic layout better than its predecessors.
Here's where things get interesting: OmniGroup gave OmniGraffle a Bezier curve drawing tool. This is a tool we commonly see in graphics arts tools like Adobe CS2, not a humble diagramming tool. A Bezier curve tool basically allows you to make any shape you can dream of, with a little practice. Fortunately, there was a Tools Walkthrough sample document which made it easy to get the hang of for the unexperienced user. For the user who needs to make a professional application, having a drawing tool included means not necessarily having to leave this application to make a shape. Of course, it will take practice to really use Bezier curves well.
To the dismay of some very picky interface design gurus I know, the tools now have a preference which allows them to be in the toolbar of the canvas window (as in versions 2 and 3) or a separate window of their own. On top of that, the tools can be docked or undocked from the canvas window. What will disappoint such gurus is that the user can arrange the tools to be in a different place, so that no muscle memory can be learned for driving the mouse without thinking about hitting the target. The good news is that you as a user can do yourself a favor- place the tools menu somewhere useful next to the edge of the screen- if you keep it in the same location everytime, you should be able to develop moving the mouse to the tools just by muscle memory.
OmniGraffle has a utilities drawer with an outliner feature. This makes it pretty simple to lay out your thoughts as an outline and have OmniGraffle lay out a diagram automatically. I can imagine using it in a meeting to make an outline of information and with no effort having a diagram to display before the meeting adjourns.
But OmniGroup goes one step further.They also make OmniOutliner. You can't actually drag from OmniOutliner into the outline drawer, but you can drag an OmniOutliner document onto the OmniGraffle app icon, which creates a new OmniGraffle document based on the OmniOutliner document. This kind of integration makes the two products a good duo, something more than just two separate products.