For stability it's best to keep up with the latest major stable
version (even numbered -- 0.2.x, 0.4.x, 0.6.x, etc). Stable versions
only receive bug fixes and performance patches so they should not
break your scripts, while unstable versions (odd numbered -- 0.3.x,
0.5.x, etc) additionally get potentially breaking API changes and
such.
The unstable versions give you a chance to see what API changes or any
changes in API behavior there will be in the next major stable version
(0.3.x -> 0.4.x, 0.5.x -> 0.6.x, etc).