Jim Dalrymple discusses the relevant questions when considering an iPad.
I use my iPad like an iPad. When I pick up my iPad I don’t think that I’m missing out because I’m not using my Mac. I chose the iPad because it fit the task I’m doing at the time.
Exactly. I use a Mac Pro for my research and I also own an iPad. I have no illusions about running complex numerical simulations on an iPad. It isn’t good at that. There are, however, many things that I prefer to do on an iPad instead of on a traditional PC. I choose to use the iPad in those situations because the experience is so much better and the overhead is so much lower.
In the Post-PC world, devices are merely form-factors optimized for particular use cases. The inability of one device to perform a task does not speak to its value. Rather, it merely means that another device is better suited. So the question of whether the iPad can replace a PC is irrelevant. Dalrymple nails it:
The right question to ask is “does the iPad fit my lifestyle?”