Sorta...
You can be SIM unlocked which allows use on other carriers / overseas.
I THINK they have root working on the S4 even with the locked bootloader. And I think only AT&T and Verizon have the newer locked up bootloader.
Interesting thing I saw on FCC about GT-i9250 is that the label is shown on a 1000 mA battery. Hopefully this is just a place holder and isn't the true size?