Good and Useful.

Great App. (Also try iTranslate, which can do Hebrew, Yiddish and many other languages.)
It requires a Hebrew keyboard, which is easy to activate from the settings on the main homepage. Press the following buttons: Settings,- General,- International,- Keyboards,- Add New Keyboards,- Hebrew.
Once you activate it, you can use Hebrew on any app. Switch languages by pressing the globe button that will appear near the space bar.
הצלחה רבה!
חיים יונה ז.

Daniel Raymen about Hebrew/English Translator