I'm listening on my iPhone right now as well, and It's a tossup for me: FStream is okay, but still needs work. It doesn't really stream well without using 3G or WiFi, and sometimes using it while charging the phone sucks more power out of the battery than the charge can replenish.
Internet Radiobox, on the other hand, shows some promise. It is also free for the iPhone (and maybe for BB), and that seems to work very well.
BL.