Can someone with more MongoDB experience give me your thoughts on the upgrade difficulty here? Worth doing soon, or waiting for a point release? Does this require a data rebuild/update process (coming from 2.4)?
"the upgrade from MongoDB 2.4 to 2.6 is a binary-compatible drop-in upgrade: shut down the mongod instances and replace them with mongod instances running 2.6."
IMO unless you desperately need one of the new features I would hold off a few weeks. With a release this big I'd expect there will be some bugs and wouldn't be surprised to see 2.6.1 shortly.