One word... HANDY!
I prefer it simply because it is more energy efficient. Electricity costs money and my lovely city just passed an energy tax increase. Anything I can do to reduce my costs is great.
I use it for reading, and it's great when you want to concentrate on one thing. I've realized I cover a lot more material when I use my iPad because it's a lot easier to get distracted on my laptop. Multitasking on the iPad, while not impossible, is harder. This is a good thing when I need to focus.
I use it in the bathroom. Of course I make sure I wash my hands
One of the main reasons I bought the iPad was that I could use it everywhere and it's not as cumbersome as my laptop. I'm a full time student and spend most of my days at a computer doing research, writing papers, etc. and it has caused some back pain. Now, with the iPad I can surf the web, access my courses online, and hopefully soon, have my textbooks on there. Now, I can sit on the couch or in my bed, which definitely eases back pain.
I'm not that productive at the moment, but since I don't watch TV, the internet is my main source of entertainment besides reading. Now I have one device for all. I'm am extremely pleased with the iPad.
I prefer it over the pc because stretched out on the couch is better than the 4 year old computer chair.
I use the iPad whenever I need to do something quick, like check the score of a game, check my facebook, Twitter, or anything that involves quick web browsing.. And more importantly you look so much cooler with an iPad than you do with any other laptop!!