XML::Atom is a module that does a good job at the basics and appears to be pretty sound in implementation. However, if you want something extensible to handle more complicated Atom-based APIs, you're going to have some headaches.
Because of a lack of thorough documentation, you'll need to dig around the source once you move past fetching the parameters used by blogging software. If you need to access complex XML extensions to the API (e.g., Google GData), you'll have to dig deeper into XML::Atom::Utils and also try to figure out how you will need to cope with the fact that this library runs on top of either XML::XPath or XML::LibXML, which have slightly different DOM APIs. At which point, I'm not sure XML::Atom provides you any added value anymore.
I wouldn't say it deserves one star, but, as is, I wouldn't give it more than three.