Is it worth buying?

Overwatch is the game you have been looking for *waves hand mysteriously*

Personally I played Paladins for a very long time before buying over watch.
Hi-Rez was doing a good job of maintaining the balance between classes as well as releasing maps on a quarterly basis.

I would try OW on one of the free weekends and see how you like it.

This game is great fun make sure you have friends to play with though