I tried the iPad for a few hours yesterday. It's the bees knees. I love it.
HOWEVER, for now it's likely going to be more an entertainment device than a productivity tool -- and that is how Apple seems to be marketing it as. It's not supposed to completely replace your laptop (but may cut into some of the time you spend on your laptop - i.e. all time you spend watching video, reading, browsing, emailing, checking scores, etc -- and the laptop becomes purely a productivity thing to do your heavy spreadsheets, editing huge documents, presentations and all the "boring work" stuff).
It's great for reading, surfing the web, checking email, watching movies, checking sports scores (you have to see the MLB app, and I haven't seen the NFL one yet) and so forth. In other words, it's more comfortable having something like this in your living room, bedroom, bathroom (you know how guys like to read while on the can) and so forth.
However, the *concept* of a touchscreen is the future (yes, Apple didn't invent it, and the technology has been around for years now, but Apple through the iPad will make touchscreen mainstream) -- it may not be the iPad itself, but the iPad is just the beginning. You may see more computers - laptops and desktops move towards this to the point where the mouse and keyboard may be a thing of the past.
I never thought it to be a big deal *conceptually* about doing everything touchscreen - until I actually tried for an extended period of time. In a subtle but powerful way, surfing the web and fiddling with applications is a completely different (and more intuitive and immersive in my opinion) of an experience when you're directly touching, swiping, dragging, tapping, etc. what you see on the screen directly (on a size that is comparable to a laptop screen with comparable resolution). It may not seem like a big deal if you do it for 5 minutes. But after playing around with it for a few hours running through applications and web browsing, it did feel weird to go back to a mouse and physical keyboard. I can imagine what it would be like being on a touchscreen computer (not necessarily the iPad, but other devices in the future) over a period of weeks or even months and years -- the intuitive aspect of a touchscreen on something that size (and not a tiny screen like a PDA) will make it difficult to go back to mouse and keyboard.
It's hard to explain, and hard to convince people conceptually - you have to really play around with it for a while before the actual experience sinks in to know that this is pretty damn cool.
But for now, the iPad likely won't replace a laptop if you're doing hardcore spreadsheets, making presentations, and writing long-ass writeups for class - for now.
However, that shouldn't prevent you from getting one.
I sure want one once the 3G version comes out later this month.