My contract expires soon and I am considering a new phone. Problem is that I have not been real happy with the Galaxy S2. On paper it is a great phone design, but as an actual working device I have had my complaints (e.g., poor GPS, short battery charge, random restarts, random application launches, etc). I would like to get someone's input who went from a S2 to the S4. As a former S2 owner, I am sure you are aware of some of the issues I have mentioned. Have they worked out these issues with the S4? Is it a worthwhile upgrade going to a S4? Or should I look at an iPhone? Thanks.