Speed
very quick. excactly what i want from a phone. No lag between tasks and can even perform under heavy load.
Screen
Very responsive as pernormal for an iPhone. The Screen resolution is amazing. Their retina Display isnt just hype. its the real deal!
Looks
Looks really sleek and feels slim in the hand. But the glass back and front leads it to feel a little fragile and makes me nervous when i take it out of my case.
Overall its is a good device but apple have let us down a bit in the design department.
(Google Iphone 4 Antenna issue and you will get a boat load of info on the subject
)