Until you try using it lying flat on a table (which I do often) and it's shaking and rattling around. Then your only thought will be "I can't believe I just spent $700 on this"...
If you're going to spend $700 in one go, without a contract, the benefits of the device would outweigh this problem.
After all, try using the first-gen iPad on a table (which people are far more likely to do with a tablet) - it moves when tapping the screen because the back is not flat. It didn't stop it being a great device and selling 300,000 units on day 1.