Good if you have absolutely no monitoring of your SharePoint site or want an easy way to understand how your SharePoint site is doing.
However IIS, and Windows Server provide more functionality than this tool if you have the knowledge set to support it. If you only want it to monitor site up time and down time keep in mind that most website monitoring software out there can do this and is also available free and most of this software has more functionality than this tool supplies.
A terrific little tool if you want to see how things are at a glance and receive email alerts when it can no longer connect to the site it monitors. I could see this being really helpful when you need immediate notification of a SharePoint site going down. Any user can probably understand the interface as it's pretty simple.
For someone who is running their own SharePoint server or doesn't have dedicated IT staff this could be a wonderful tool.
The thing is that out of the box your Windows Server should provides more indepth performance and IIS monitoring solutions (from what I can see) and since the free version of this product is pretty limited in what it monitors/how you can configure reports I would recommend that a professional (dedicated IT staff) organization shouldn't really be looking at free solutions like this, or should be looking at more comprehensive solution sets.
3. Easy to Install
4. Easy to Use/Understand
2. Simple set of 6 'reports' via visual indication that only shows a window of information. Cannot generate larger reports for usage over months etc with this tool without manual intervention.