The biggest part of the update is that Apple now allows third party applications to run on your watch. This will enable more functionality including something that Apple calls "complications." This is not the best marketing name but Apple said that it means you can have a watch, flight time, top story from the CNN, temperature and time at home, all in one screen.

Apple will have its own maps on the watch, it will tell you transit times, and you can reply on the email via voice dictation.

The new update will bring the new watch faces, and it will let you make watch faces from the pictures you own. This is such a nice feature which was copied from the much mocked Zune MP3 player a few years back.  The new watch faces will show you a time lapse picture of some cool cities and natural resorts in the world. It looks good on video.  

This is new to WatchOS 2. If you turn the Dial crown on the watch, you can see new appointments and there is always a night stand mode that will tell you time, alarm time when the watch is charging – which will still be most of the time.

Overall it is a nice and free update and if you already have a watch, you should go for it.