No way am I going to the s4. I had the s3 for a month and was miserable with the lack of signal, failed calls and texts. There isn't a huge difference between the s3 and 4 outside of a slightly larger battery and screen and the quad core processor.
I used my Nav yesterday (Flawless and immediate) - S3 was hit and miss, many times no lock at all and when it did, had me driving in circles.
I actually made and received calls from my Basement. - S3 had "NO signal at all and if I went upstairs it was sporadic at best.
On Day #3 (will charge tonight, Maybe) that is typical for my MaxxHD - S3 Never made it through the Day (1 day)
Couldn't GIVE me an S4. For those who "Have to have one" - Good Luck, Wish you the best (Wish being the operative word)