It's not remotely close to being the best phone on the market. The best phone on the market wouldn't have so many volume issues WITH THE ACTUAL PHONE PART OF THE PHONE. Fix this garbage, Apple. Who gives a crap if you can email your friends from the phone if you can't hear them when they call you?
I know saying 'relax' isn't going to help, but I'd have to say it anyway. I've found a number of the complaints labeled against the iPhone are reminiscient of the initial release of the V3 RAZR way back in the day. File system issues, low call/speaker volume, lack of video recording, poor batter life. Each of which was fixed by firmware updates from Motorola. I expect exactly the same with Apple and the iPhone. Unfortunately yes, it will probably take a little bit of time.
In a Mustang V8, with the windows down and doing 75 MPH in medium traffic on the highway I could hear a caller just fine on my iPhone at 3 notches below max volume. That to me was impressive considering the environmental noise, but I don't doubt some people have volume issues. I notice my speakerphone volume is pretty poor, though I believe that to be more of a software/firmware issue, as playing videos/music through the speakerphone come in MUCH louder than call volume. I expect Apple will eventually rectify this and other issues.
I'd also point out that some of the 'exploratory work' being done on the iPhone could also yield very interesting results. Before Moto addressed the volume problems on the V3, people found a way to modify the gain table enough to actually make the speaker loud enough to permanently damage itself! They also found how to add video support before Moto did via seem editing. Heck, there were even custom firmware releases that ripped out all the Moto fluff (ringtones, videos, wallpapers, screensavers) that you couldn't delete to almost double the available space of the phone. On the A1200 they figured out how to fix the speakerphone so you could use it with the flip closed, and even found a way to activate EDGE support when most people thought it didn't have it.
I respect the issues people have been having, but they are not really at all surprising for a large scale cell phone release, and I expect within the next few months Apple will address a number of them.