Performance
Intel Core i7 is a high-end processor. The higher clock speed, bigger cache and hyper-threading features in i7 processors make them more suitable than i5 processors for certain applications like video encoding, data crunching, graphics-intensive work, multitasking, and high-end gaming.
Gaming Performance
According to a study by APC, the difference between the Core i5-3450 and the top-end Core i7-3770k is about 10%. With 1080p, the i5-3450 delivered 81.6fps on Crysis, while the top Core i5, i5-3550 delivered 86.7. The i7-3770K delivered 89.3fps.
Video Editing
According to APC Magazine, there is some benefit to using i7 if ripping DVDs and converting them to .MKV files. However, they suggest that the i5-3750K is the best...