LOL the back translation was a bit garbled when I ran it through again...
I had Google Translate from English to Polish... Here's what Bing says for the same.
Witamy w najlepszym przyjacielem telefon jakie kiedykolwiek miałem.
The back translation looks better with Bing and just as poor with Google. (Good to know)
The original sentiment was: "Welcome to the best friend your phone ever had."