One of the best!

The Nuance Speech Engine does a fantastic, accurate job. The GUI interface is very simplistic but practical. The accuracy of the translation is fair. Its one of the best of the many I have tested.
The only major insufficiency for me is that it does not speak Hebrew although the voice translation is handled well. There is almost no translation app out there that handles Hebrew voice! Come on guys, lets get the Hebrew working in your future upgrade for a full five star rating.

AltairGenesis about Voice Translator - On the Fly Translation, v2.3