iPhone 5 will be announced within a few hours, so here's the weigh-in on what to expect versus what's already out there. iPhone 4 was hugely popular, still sells and costs a bundle. But with the iPhone 5 launch, some of the iPhone 4 features won't seem as appealing because they will have been upgraded. A faster smartphone with more memory will always be just around the corner, and dual core and even quad-core phones are soon to be the norm. Those are good reasons to upgrade. Start the slideshow to see the top 10 reasons to upgrade to Apple's newest iPhone.