It seems pretty good to me. It uses the headphone cable as the antenna, and have used it once where I had no mobile phone signal (In a kind of basement room), but the FM radio still worked fine - it wasn't 100% clear, but a good 90%.
If you're referring to the FM radio,it's pretty good. The phone comes with an "FM radio" app which comes with 6 presets, and you also get the ability to record live radio sessions. It does use your headphone cable as an antenna, and it seems to be very picky.
Like Mike mentioned before, most carrier versions of the phone have the capability disabled. Some of the versions out are: H850 (Europe); VS987 (Verizon); H820 (AT&T); LS992 (Sprint); H830 (T-Mobile); US992 (US Cellular); H860N (International dual sim).
I would go with the H860N (has all the bands to support most of the carrires) if you really want the full functionality of the phone with no restrictions, and no added carrier bloatware.