The iPhone 5 screen is beautiful. Benchmarks say it's the fastest phone you can buy. Leo isn't sure that's as big a deal than it used to be, though. Apple says it's the thinnest iPhone ever, but it still feels dense. The screen is an odd - a 16:9 aspect ratio at 4 inches. Basically, it's one icon row taller (176 pixels), and the same width as before. The size isn't a big deal, but the real benefit will be noticed when watching widescreen videos.
Leo's been using iPhone 5 for a day and hasn't really noticed it being really appreciably faster than his Galaxy SIII. There's two questions about the iPhone 5. The significant difference is that it has one extra icon row, or 176 pixels more. If you're in an LTE area, it may be worth it because of the fast connectivity. Running a speed test, Leo got 27mbps down and 15mbps up. That's faster than home internet, but that means you'll burn through your data caps faster too.
Leo says it largely depends on if 4G is in his area for his wireless carrier. It also depends on how he uses the smartphone. If he's a heavy user of data, then 4G/LTE is a good option. He also wants to be able to surf online while on a phone call, and Verizon's LTE network would allow that as opposed to their 3G network. If he's happy with his current phone, there isn't a compelling reason to upgrade to 4G. Battery life also isn't near as good on the 4G/LTE phones.