Visio 2007 as a standalone project management tool is what you would expect. It's not specifically designed to be a project management tool that can stand on its own. Having said that, there are some useful tools that Visio 2007 provides which can enhance a project manager's arsenal. For example, you can create a project schedule directly within Visio 2007 using the default scheduling templates provided.
When you first open Visio 2007, you will see the Getting Started page. Listed in the left pane are the various default template categories, one of which is Scheduling. If you click on that link, the right pane will show four templates - Calendar, Gantt Chart, PERT Chart, and Timeline. You can also get to the templates by clicking on File -> New -> Schedule and choosing one of the templates listed there.
Double-clicking on the Gantt Chart template creates a new Visio drawing based on that template. You are then immediately prompted to choose the various options for the chart. On the Date tab, you get to choose how many tasks to create, what the Timescale range will be for the chart, and what the major and minor Time units will be. If you switch to the Format tab, you can modify what symbols will be used (if any) for the various parts of the chart. Once you click Okay, Visio will create the chart according to your requirements.
From this point, you can double click on any of the fields in the chart and change the actual data for each listed Task. The interface is very similar to using Microsoft Office Project 2007. You can change task durations either by changing the Start/Finish dates or you can just drag the bar length in the Gantt chart itself. If you right-click on any Task, you can insert a new Task from the menu list. If you highlight multiple tasks, you can create relationships between them (i.e. one task dependent on another's completion, etc). On the left hand side you can leverage Viso's graphical abilities by dragging over Link lines, callout text boxes, milestones, or even a Legend for your chart.
Once you have your schedule created the way you like it, you can print it or even save it in any number of different formats. Sure the functionality is limited when compared to Project 2007, but there is definitely enough here for basic project schedule creation. The interface is clean and easy enough to understand, particularly if you're already familiar with something like Project 2007.