Previously, jFitbit relied on the XML endpoints that backed the Flash-based graphed on fitbit.com. With the advent of the new online dashboards backed by ("/getNewGraphData"), jFitbit migrated forward. While the same basic raw data is available, derived activity and summary data is not as readily present.
Along with a refactor of the data models, daily-resolution queries have been removed; instead this client focuses solely on providing intraday-resolution data. This release also find new added access to weight measurements and tracker status.
This update isn't plug-and-play with previous jFitbit releases. Presumably you can continue using the 2.x client if desired, but I have no clue how long Fitbit will continue providing the older XML endpoints ("/getGraphData").