Is the i-phone that great?

I have a few problems with the iPhone. First of all the price it is way too expensive! Who would pay $500-$600 for something to make calls on? Second, it only works with Cingular. I don't have Cingular, and I don't have many friends that do. so they or I will never be able to get the iPhone. Third, what is multi-tasking? And finally, there are so many comparable products, that the iPhone is just another knock-off.