Works very well for me. I'm using OS 188.8.131.52 and it works there. What OS are you using? Try checking in your Options | Applications listing, if you see it in there, delete it, then pull the battery. When the phone comes back up, then go to Download | Viigo
from your mobile browser.
Note that you have to select the correct version of Viigo to download, either for BIS or BES.