My Dad has a Parkinson's like disease.
His fingers move very slowly and so he gets multiple repeats of lettttters, like that.
Is there a way to slow down the keyboard response to that he can get his fingers off the keys before the letters repeat?
Which version of iOS are you using? My brother has an iPad 1 running iOS 5, and keys don't repeat at all. Instead, if you hold them down long enough, you get the option to chose special characters, but if you don't choose any special characters you still get the letter you pressed. iOS updates are free, so if I were you I would update to iOS 5, which should fix your problem. (You can do this by plugging your iPad into a computer, opening iTunes, clicking on the iPad in the sidebar, and clicking the 'update' button.)
Although there is currently no way to adjust the key repeat rate on iOS, one solution may be to find a usb keyboard that your father can use. Getting a keyboard that has a large travel (the keys are tall, as opposed to the more modern slim keys) might help with this.
Using the Camera Connection Kit from Apple, you can connect just about any USB keyboard to an iPad.
Lastly, take a look at