I've only had the phone for a week but would like to give a review right now.
The phone has a good response, there is no noticeable delay.
The battery discharges very quickly though. I myself do not think I use the phone very much. I have no games installed, I use it mostly for email, twitter and listening to music when I am outdoors. The mobile charges very quickly, so if you have access to an outlet, there is no major problem. And nowadays there are chargers that you can take with you so it's not the whole world.
There are many cool themes for mobile that you can download via Samsung's app, there are both those that cost and free.
I wish there were more options for contacts. For example, giving different contacts different SMS signals and vibrations so far, I have only found how to change the ringtone to different contacts.
Voice to text feature works very well. I have written this whole review by talking to my cell phone. It sometimes happens that it writes the wrong words or sentences, but for the most part it writes correctly.
So far, I am happy with the phone and recommend it. If my opinion changes, the review will be updated.