It’s still just an iPhone. This is a nice piece of hardware, no doubt. But it won’t do that much more than your iPhone 3GS, which will be capable of multitasking, can shoot decent photos and videos, has the same maximum storage options, and operates at the same network speeds. Unless the new camera and flash, screen res and video chat—which is Wi-Fi only, and connects exclusively to other iPhone 4s for now—are things you absolutely need, this is a non-essential upgrade. Apple is the king of incremental upgrade and iPhone 4 is no exception.
The article gives sound advice. Looking forward to iOS4 to be released.