Many people are certainly rushing the retail counter and as hot a ticket the iPad is, I think I found one good reason not to buy one: a weak 3G signal.
I have had mine for a few weeks now and realistically could have done without. I have been a Mac user since the late '80's .. run three at my business and have a Powerbook Pro ... and I will not be selling my iPad, but it will be collecting a bit of dust.
For me - the perfect use for the iPad is for a 'home' computer ..that slips into a small bag and carries but does not need to run Photoshop CS5. It would be perfect for my wife who has a lot of distant friends where she could check/send email anywhere she happened to be. There's no way she would, or need, to carry the PBP for her uses.
I would probably buy another iPad had it worked out that way. (Actually, this was to have been the camel's nose under the tent to convince my wife to convert both my business and home to iPhone and give the stalinists at Verizon the boot.)
My home however is on the fringes of the signal. So far, I have spent about $450 to get an antenna and repeater to snag a signal with little to show for the effort. The iPad works perfectly at my shop, but this iMac is already well connected via DSL.
I went to Los Angeles for a few days a week before the iPad came .. and it would have been a helluva lot better to travel with it vs. the MBP .. especially given all the space and luggage limitations of air travel these days. If I traveled more than a few times a year, that alone would justify the purchase.
I do not live a 'poor me' life. I give almost anything a 100% effort if it shows promise. If not, I look forward to the next adventure.
...but if someones asks you: tell them to make sure they get a good signal - a really good signal.