Water resistant

The phone itself? I doubt it. But if it is important to you, you can buy the Otterbox Armor Series for like $100 dollars extra.

carousel-armor-splash-2.jpg
 
Check out the link in the OB thread. There is a link to the OB cases for the GS4. The Armor series was not included.

Sent From My Samsung Galaxy Note 10.1 Tablet
 
Do you think this phone will be water resistant like the Sony Xperia Z.

Not at all, and that's a good thing. The Sony has all of those port covers that the s4 won't have. And the screen quality took a big hit due to the water proofing and that's something no manufacturer is going to do to their flagship phone meant for general usage. Not to mention the fact that it's a plastic phone with a removable back....

Sent from my Note 2
 
To answer your question, no the Samsung Galaxy S4 is not waterproof. I don't really get any anyone would need a waterproof phone. I mean seriously, using your phone in the shower? Wait until you get out of the shower, then use your phone. However, I can understand if you are one of those people who needs a waterproof phone for "just in case".