On the computer desktop, the Apps Store is integrated into iTunes. You can browse, purchase and/or download apps from iTunes, then synch them to your iPhone. On the iPhone, the Apps Store is a separate widget. But like the iTunes widget, you can buy/download apps directly to your iPhone, then synch them up to your computer.
One of the most astonishing paid apps I’ve seen is Intua's BeatMaker — a sample-based beatbox with pattern and song sequencing that works like something straight out of Native Instruments' Reaktor. It comes with native kits as well as kits provided by artists of Richard Devine's calibre. Presumably, you can also download samples and kits you create to your iPhone and upload .wav files of projects from BeatMaker to your computer. But so far, I have not been able to get the Beta computer desktop server to talk to the iPhone. Regardless of what may be plaguing the Beta server, the app itself works just fine in its native iPhone environment. The fact that iPhone can support this level of programming sophistication demonstrates the robustness of the iPhone API. BeatMaker is not a full-featured DAW (digital audio workstation). But add a piano roll and a few synthesizers and it soon will be.
Given that this is the starting point for third party iPhone application programming, I look forward to seeing the iPhone apps of the future.
All in all, the iPhone 3G is an improvement over an already great gadget. I can’t say that first-gen users need to upgrade. But the better application performance alone definitely makes it worth an upgrade.