I picked up an iPad when they first shipped in the UK at the end of May. Here's some random observations after three months of use.

It's no match for a desktop or laptop for continuous desk use. I hardly never use it when I'm at my desk.
Since I got it, my previous out-and-about device; my 15" MacBook Pro, has turned into a desktop. It never leaves the house and having an iPad will probably considerably extend the time before I replace the MacBook. The iPad is small enough to go pretty much anywhere and last for hours which is a big plus.
Every time I visit the App Store I'm disappointed by the same old apps always being in the featured section. Like for months. Doesn't feel like there's a massive amount of iPad app coding going on.
Screen smudges and smearing is a real niggle. I have invested in several strategically placed microfibre cloths around the house, in my case and in the car. I hate using it in smear mode, particularly in bright surroundings.
The Apple case is shit. Functional, but too 1990's in design. Get a Dodocase.
I'm being ground down by Update fatigue. This doesn't only apply to the iPad, obviously, but literally every day (sometimes multiple times a day) my App Store icon shows a little red badge number indicating one or more of my apps has an update waiting. This is a bigger topic which deserves its own post. And it's my fault for having so many apps, but it's growing tiresome. They should have a weekly update day, or something.
Apple's spreadsheet app, Numbers, is pretty shit. Just an elaborate viewer all told.
It's a pain that you can't sync AND charge it with USB (on my 2006 Mac Pro anyway). I now have an extra white cable on my desk.
It's cool that iPhone apps scale up to run on it, but it really is a compromise. Before long you get narked at the pixelation.
It isn't the second coming of Christ, but for a first go it's closer than any other device to earning that description.