If I were a young grad student again, I'd do it in a heartbeat!!
The advice offered thus far is sound; learn the language of the host country as thoroughly as you can, no excuses!! Be it Poland, Germany, France, whereever. You will not only be closer to being treated with respect and not feel like an outsider, you'll gain the confidence to understand the locals without having to rely on their often broken English. Besides, even when they speak English, they almost never say what they're really thinking in a way that makes cultural sense to a non-native-:))
Almost forgot. When I was studying Polish in my early thirties, I had the chance to take Polish classes at Jagiełłoń University in Kraków for a summer, sponsored by the Kościuszko Foundation, i.e. a freebee language vacation!!
Like an idiot, I turned it down. Actually, had I not been in the process of getting married at the time, I'd definitely have gone over to Poland!
Shoulda, woulda, coulda, huh?