I've had my S4 for about a month now, coming from a Motorola Atrix 4G. I love my S4. The screen size is perfect. I can use it one handed 95% of the time. (Something I was concerned with.) The Super Amoled HD screen is just beautiful and everything is very sharp and colors look almost life like. (There is some over saturation, which can be changed in the settings menu.) Reading books, magazines and watching movies is just awesome and looks great. Text and emails are so clear and sharp. The 13MP camera is just great. Love all the features and modes you can select. It can take great close ups and 4X digital zoom with great detail. Really like that I can be video recording and take still pictures at the same time. (Pictures are pretty good, not as good as if you where just using the camera only.) Its a very fast phone. I have had some lag, but not sure if it was due to the 3rd party launcher I'm using. (Doesn't happen often.) Most of the S features I don't use in everyday life, but find them to be useful for when I need them. The speaker is very loud and sounds great, but lacks bass. Since I have 9 different calendars to keep track off, the Stock calendar app is just awesome and really easy to use. Love the earth tone color and transition affects.
My S4 is lighter and thinner then my smaller Atrix 4G. (I was surprised about how light it is.) The notification bar with all the quick setting buttons, that can be customized, is really nice. I like how the settings are broken down into 4 tabs: connections, my device, accounts and more. I ended up taking my 16GB version back for the 32 GB version because I ran out of space once I transferred everything from my Atrix 4G over. (16GB= 9GB of personal storage; 32GB= 24GB personal storage.) One thing I wish my S4 had that my Atrix 4G has, is the "USB Mass Storage" option when hooking up to a computer. On my S4, when I'm transferring pictures to my computer to my Kodak Easy Share program, it doesn't see my S4. So I have to first transfer the pictures to a picture folder, I created on my desktop, then transfer them to the Kodak program. (It's not heard, just more steps to do the same thing.)
The battery life is great for me. I get on average around 12 to 14 hrs using wifi 90% of the day, bluetooth about 10%; GPS 5%, sync set for every 4 hrs for email, about 1 hrs of web reading and 3 hrs on screen time using auto brightness. (The screen is almost 40% of battery drain.)
I use "WatchON" more then I thought I would. Its a really cool feature. Since our remotes are not back lite, using my S4 to change channels in the dark, schedule recordings or see what's on TV is a handy feature. Using "Flipboard" for my news, all in one place is really nice and you can customize it to what you want to see.
Bluetooth works well and devices connect quickly. Although my 3 yrs old Plantronics bluetooth I have to open up bluetooth settings and select it to connect, even though its paired. (I don't think its a Samsung thing.) I like the dual display mode too. Really helpful, but limited. I have over 245 apps and only about 10 of them are capable of using this feature.
There are other phones due out in the next few months that will go head to head with the S4 in specs, etc. I feel though that the S4 is future proof for at least the next few yrs. Samsung is really good at pushing out updates, which is really good.
