I went with the 16 GB iPad without UMTS/3G for a few simple reasons:
- The iPad is not meant to be your main storage device. That's what your Mac/PC is there for. If you want to watch a video on it, you'll copy it to the iPad, watch it and then delete it. Period. You'll probably won't be using it as your mp3 player either. Why? Because there is this thing called iPhone in your pocket. That leaves eBooks, and an eBook is smaller than your typical mp3 file. So unless you want to carry around the Library of Congress, you won't need much storage for that either.
- The iPad is not the mobile device everybody seems to believe it is. You'll use it mostly in bed, on the toilet and as a reading device in your living room or on your desk. You won't take it in the park with you because its display sucks in bright daylight and you'll be afraid that somebody might steal it from you. It's also just to big. For outside reading, buy a Kindle. You still have your iPhone for the rest.
- The iPad will also not replace your notebook. It sucks for writing unless you use an external keyboard, you cannot copy and paste between apps and apps cannot share the same files because there is no common file system. This quickly kills the iPad-as-a-notebook-replacement dream.
So what is the iPad? With its limited hardware and restricted operating system, it's basically only a (semi-)mobile surf board, eBook reader and game console - that's what it can do quite well. For everything else, the software is just too restricted to make it really useful.