I've had a F320S for a couple of weeks now. Setting the default language to English was really easy. The main frustration I've had is with all the bloatware included by the Korean carrier.
Mobile T World, Mobile T Money, NateOn, MelOn... got knows what any of this stuff does. The only part that's English is the apps name. I've ended up freezing the applications and it's gone and forgotten. There were about 20+ apps that needed to go, but being a bit of a geek; it does irritate me that they're still taking up space.
I did try installing a new ROM but it failed multiple times (not the easiest device to flash apparently) Still, there haven't been enough irritations to turn me back to Apple.