I have; and I think you can't compare something priced at $100 to something that costs twice, three, four times the money. There will be compromises, but to say they are unusable like others suggest, that's not accurate.
I clearly stated that it cost as much as an iPad. Here's the link to the tablet on amazon:
http://www.amazon.co.jp/docomo-ARRO...TF8&qid=1389087985&sr=1-7&keywords=ARROWS+Tab
It's ¥50,000, which is about $500. (I live in Japan)
I'm not sure you can get get your hands on one of these, but if you do, you'll find out what I said was true.