The 3 issues reported with the app are:
1. Using voice search outside the U.S. crashes the app.
2. App doesn’t work on 1st generation iPod Touch.
3. No search results outside the U.S.
Over at the Bing blog, they have published a temporary workaround for 2 issues which is quiet simple to follow. On your iPhone or iPod Touch, Go to Settings > General > Internationalization and change your region format to United States. This will allow you to use voice search outside the U.S. without crashing the app and also show your search results. When the update is released you can change it back to what it was before.
Check out our review of Bing App for iPhone and iPod Touch.