I must agree with @Roshan – it's hard to imagine anything more intuitive and easy to use for atomic batching as old sync batch api. Also, it's fast. Coupled with a separate instance of producer per broker:port:topic:partition it works very well. I would be glad if it finds its way into new producer api.
On a side-side-side note, could anyone confirm/deny if SimpleConsumer's fetchSize must be set at least as batch bytes (before or after compression), otherwise client risks not getting any messages?
