Do we get any advantage if we use Axis 2 directly instead of Jax - WS .
JAX-WS is an API, while Axis 2 is an implementation of that API. So the choice is not between Axis 2 and JAX-WS, it is between Axis 2, Metro, and all the other existing JAX-WS implementations (the differences of which you can look up on their respective web sites, or search for the recent discussion on that subject in this forum).
Also read that to use JAX -WS we need java 1.6 version or more .Is this true ?
No. Java 6 includes JAX-WS and JAXB, but those libraries can be downloaded and added to Java 5 as well.