Launched today... Lots os 'smart features' like:
* smart pause: pauses video when you're not looking at screen
* air view: place your finger over the screen (hovering) to preview items like messages, photo albums
* group play: share music, documents, games with a few other devices
* dual camera capture
* etc...
heck, can even use it as a TV remote controller
goodness...
see:
http://bgr.com/2013/03/14/samsung-galaxy-s-4-release-date-specs-374917/
http://phandroid.com/2013/03/14/samsung-officially-announces-the-samsung-galaxy-s4/
http://www.techradar.com/us/news/phone-and-communications/mobile-phones/samsung-galaxy-s4-release-date-news-and-rumours-1089523
http://reviews.cnet.com/samsung-galaxy-s4/
http://www.huffingtonpost.com/2013/03/14/galaxy-s4-features-samsung-smartphone_n_2878956.html
http://www.theverge.com/2013/3/14/4104072/s-health-turns-the-galaxy-s4-into-a-full-fledged-fitness-tracker