The iPhone 4s is a gradual step over the iPhone 4 improving the internals, but keeping the look and feel. At the same time, though, it brings a reworked iOS 5 and introduces Siri, a personal voice assistant allowing you to vocally communicate with the iPhone. It comes with a 3.5" screen with a resolution of 640 x 960 pixels, but on the inside there's a twice more powerful dual-core A5 processor. It also improves connectivity a notch, bringing 14.4Mbps HSPA download speeds. The back is where an 8-megapixel camera resides and it's capable of recording 1080p videos.