I've purchased and installed this app and am excited to use this in the field, but have currently found all the OCUS caches near home.
The app does seem to be fully in English, now, but when authenticating you will be taken to a page on this site that is in Polish. I need to double check the location of that and see if we can fix it. Don't worry, the only thing you'll need on that page is your authentication number.
I had one problem getting authenticated on my Droid2. After seeing the authentication code, if I slid the physical keyboard out (rotating the screen), the "Authenticate" button would become grayed out. I had to end up using the touch screen keyboard to avoid that and was fine.
They have a Facebook Page
or, if you can read Polish, you can also visit their website
When you look for them in the Android Marketplace, search for "OpenCaching for Android