In the Noda Time User's Guide, the rationale section states:
the public API has been largely rewritten, both to provide an API which is more idiomatic for .NET, and also to rectify some of the Joda Time decisions which the Noda Time team view as "unfortunate". (Some of these are simply due to having different goals; others I'd argue are really mistakes.)
What are these decisions that are different/better? This would not count differences just for language syntax, but would include anything done to make the users less likely to make a programming error (library usability).