Appearance:
This is a rich command-line tool. It is possible to extract any metadata available for any data package on the site that is available through OAI-PMH.
Potential Problems:
When querying for total data packages and total data files, the numbers that are returned are substantially higher than what appears on the homepage for datadryad.org. Ryan guesses this is because the number from R includes datasets that have been deleted, and R is failing to account for those that have been tagged deleted.
Recommendations:
We should communicate the above problem to the developers of ROpenSci.
http://wiki.datadryad.org/External_Metadata_Use#ROpenSci