I think the problem you'll find is that the audience for what you want isn't learners of Japanese as a second language but Japanese schoolchildren (and to a lesser extent adults).
While I've come across input systems the only educational program I've seen was for Japanese schoolchildren that didn't seem to be on public release.
http://www.d-dorazemi.com/index.html
An excellent pen input system -->
http://www.visionobjects.com but it won't give any feedback.
A much better bet for what you want is Nintendo DS. Although the feedback is in Japanese and the programs are only available in Japan.
http://www.nintendo.co.jp/ds/avmj/index.html
http://u-can.sega.jp/
Both these titles give detailed advice and feedback.
http://100mas.jp/kakitorikun/
Kakitori-kun is a great program but while it does teach writing Its feedback is limited. It's more geared towards learning readings of words.
Maybe you have a DS already. They can be bought fairly cheaply second hand. The larger screen of the XL model is better for writing. The software is harder to come by outside Japan though. Within Japan you can sometimes find them cheap in Book Off.
iOS doesn't really have what you want either. Fingers aren't good for writing with.
If you want pointers for good handwriting have a look here.
http://www.geocities.jp/ki07ji/muryo/muryo.html
