This is a beautiful extension, especially if your run an ecommerce site, such as Virtuemart. One of the main reasons I cannot use the default Joomla page cache is there are certain modules that cannot be cached and there is no option to keep sections of the page uncached. This plugin solves that. I have used it on several client sites now and it is working flawlessly.
You do need a tiny bit of programming knowledge to understand how to keep module positions uncached. But for something that is free and does the job very well, cant complain.