We purchases iTaskX about 6 months ago, and I've used it in several applications. The software is well-suited to relatively simple projects of a few hundred tasks and a dozen resources. The input is straightforward, and there's ample help. There are a few annoyances (like why is there a 7% increase in resource costs if input as $$/year instead of $$/mo or $$/hr?) that you have to work around, but the iTaskX is very serviceable.

If your project is complex, however, the software is not up to the demands. I tried to cost out the annual strategic plan for a small firm of 10 employees. It was a mess. You can't use common resource lists, or separate projects into sub-projects/master project, and reporting features are very limited. Cutting and pasting tasks across sheets drops the resource assignments, and so each task has to be assigned by hand in a rather tedious manual process. I'm ashamed to say I had to get VMWare and use MS Project. And even then, the importing of iTaskX xml files into MS Project was not seamless, as claimed.

Overall, iTaskX is fine for small projects, but is not yet up to the task of complex projects.