Normal for the device, but no doubt though to me it runs at a little higher temp than the S3 for general use. Again, same fabrication of silicon, same size, but faster chipset, higher res display and lighter. How would it not?
The S3 gets real hot too when running GPS and in weak signal areas. The combo of the GPS radio and the radio trying to pull a weak signal is going to get hot. I have noticed no difference in radio quality with the S4 compared to the S3 on VZW network (for my one "whole" hour of use). That said, I did notice the S3 was 1 to 3 dBm better with signal than the S4. Did not get to venture into weak signal areas to test which device would wimp out first, but medium to good signal areas the S3 was a tad better with signal.
I still want the S4, so will cross my fingers a 32 is offered by VZW. Can not help but think though that VZW has one specific finger directed at their customers....