There are only a couple of problems with the
iFM. For one, it doesn't seem to have the best antenna. Though the system was able to pick up all of the major stations in my area, there were a couple of smaller (granted also weaker) stations that I typically listen to that the system either didn't pick up at all or were so filled with static that it wasn't worth it. This can probably be overlooked in bigger cities where there are several of stations of each type, but when you get into smaller cities or towns, this could be an issue.
The other problem happens whenever the PSP goes into hibernation. When the handheld sleeps, you no longer have any control over your iFM. If you want to change the station or even change the volume, you have to wake up your PSP and then make the necessary adjustments. This can be a problem if you plug yourself in at work or while on the treadmill and suddenly don't like the song that's on. This is different than when I am listening to my MP3's because though the screen shuts down, the system itself does not hibernate and I still have control over song-choice and volume from the remote (both the one that came with it and the remote-mode of the iFM.
In general, Griffin's iFM for the PSP accomplishes what it sets out to do. It lets you listen to most of your local FM radio stations while not draining to much of your battery life, and with a simple flip of a switch it can be used to replace the remote that is bundled with the system.