Choose your Java Wisely

Java has come along a long way.  Many would agree with this.  I did not until the Java 1.5 "Tiger" hit me.  The tiger had several new features, and more importantly, it has new syntax.  Six major upgrades that the tiger presents are certainly the generics, enhanced for loop, autoboxing (unboxing), improvement on Typesafe enum, Static import and the metadata.  Of course there are many more, which can be found at java's official site.  Out of these six, at least four would be used in my daily "programming" life.  From java 1.1 to 1.4, it seemed more like new frills were simply added.  It felt like earning more brownie points when you downloaded the newer version.  But should I start using 1.5 immediately, maybe not.