2.1.x and forward has settled down a lot. They're still doing a lot of work under the hood to improve HTTP pipelining and other fun things. Worth reading their future roadmap.
Seems the Android guys are facing the same problems with Groovy in their Gradle based build system, and the Gradle team are considering switching to Scala for Gradle 2 to keep Android on board.
Needless to say, if you think 1.2.5 to 1.2.6 is bad, don't ever upgrade to 2.x!