Iphone 4s is a very good smartphone as I personally used it for 5-6 months. Basically, I was using a high end model of 64GB storage but I was amazed to see the super speed that it has with just 512MB RAM.
Sound quality is also quite good as iphone is best in their sound.
User Interface is also very friendly and not much confusing. Its very easy to use.
Style and design are also good with Gorilla display or mirror finish on both sides.
Its a fully featured phone and if you are planning for it purchase it guys.
All in all its a good product from Apple.