I bought the 8GB iphone. It's a very slick device. The functions that it was designed to do, it does well. Bluetooth is crippled since it can only hook up to a headset, you cannot sync the device through bluetooth or wifi.
Does it replace the N800? Not in all tasks. I like the web surfing experience I get with the Iphone and the touch screen is more responsive than the N800.
It's a little sad that this device will have to compete with the N800, since there are a lot less people into the whole Maemo Linux enviornment. The target consumer for the Iphone has a much larger population on the N800. I am afraid that development for the N800 will suffer.

A lot of people do complain about the device, and I don't truly understand their gripes since I am not in the same situation as they are. The iphone just simply works as it was shown in the Keynote and commercials. People probably don't think that it is worth the 500 or 600 dollar price tag for its limited functions. Then again, is any phone or internet tablet worth $600? We always want the most for our money, and a device that we can enjoy. I had that same feeling with the N800 when I got it, now I have that feeling with the iphone. I am sure in another year, some company will make a device I will crave and spend insane amounts of money for... Maybe even a google phone.. the gphone?

Getting back on the topic a little, I hardly consider the iphone a flop, its seems to be a winner. The hardest thing to do is to get normal people to part with their money... and apple did that.. amazingly.