Tux I agree that Spreadsheet::XLSX is buggy. However, it is my experience that XML::Twig segfaults due to a perl bug in Windows perls prior to 5.15. Since Spreadsheet::ParseXLSX is built on that it makes both of these packages buggy for a certain population of users. (Which is partly why I wrote my package on XML::LibXML.)
On the other hand I have run into a lot of implementations of both of these packages where people are quite happy with them. Additionally for small spreadsheets where you are only extracting data and not formats, Spreadsheet::XLSX tends to be faster.
update:I think Spreadsheet::ParseXLSX also fails to open Excel sheets that contain dedicated chartsheets (not worksheets). The
XML::Twig RT que is a bit daunting, and the
current release on CPAN testers has open fails. Otherwise I agree that Spreadsheet::ParseXLSX is a really great module.