We were impressed with the TuneTalk's performance, when recording loud, short-format sources, that is. It saves recordings as CD-quality (16-bit, 44.1KHz) WAV files, and they sounded fine from both live and line-in sources when the recording volume was near maximum. However, with quieter sources, such as an interview conducted via speakerphone, we heard the iPod's hard drive clicking in the background of the recordings. Serious audio archivers should look elsewhere--probably at a non-iPod MP3 player with line-in recording capability built in.
Also, be prepared for the stereo recordings to take up a boatload of space. These WAVs use about 10MB per minute. If you want to save disc space at the expense of stereo sound, you can also record in Mono (22.5KHz) to create files at half the size.
To test the TuneTalk's battery life, we started recording with a fully charged, moderately used video iPod. After a mere 15 minutes, the iPod's battery meter showed a nearly depleted battery. However, as Belkin notes in the manual, the iPod underestimates the remaining battery power when using the TuneTalk, due to the high level of hard drive activity associated with recording audio at a high bit rate. (Another confirmed side effect of the constant hard drive spinning is that our iPod heated up significantly while recording for long durations; it's tough to say whether extended TuneTalk usage might eventually cause excess wear and tear.)
Ignoring our iPod's waning battery meter, we were able to record audio using the high-quality stereo setting for about an hour and a half with our fully charged iPod, whether from the microphones or the line-in jack. This is not enough for some live shows but perhaps enough for one band's set or an album. In low-quality Mono mode, our (again, moderately used) test video iPod was able to record for nearly two hours. For optimal battery life, you'll need the latest firmware version on your video iPod.
If you're near a computer with an open USB port, you can recharge while recording if you eject the iPod from iTunes, but an optional battery pack would have been a better option for extending battery life. Another quibble: when the battery does die, the last 25 minutes of the recording is unplayable, meaning that you have to select Stop And Save before the battery dies using an unreliable battery indicator (or your watch).
As far as accessories go, Belkin includes a clear plastic spacer, which allows the TuneTalk to be used with video iPods in their cases; a USB cord; and a little stand that holds your iPod near vertically on a table to aim the mics at your recording source. This folding plastic stand is insubstantial and somewhat fussy, but the upside is that it's small enough to fold into your wallet or iPod case.
Overall, Belkin succeeds in adding a high-quality audio recording feature to the iPod, although processor requirements create a fairly serious battery issue. Video iPod users looking to record high-quality audio will find that it works great for short-format recordings. The TuneTalk is perfect for mobile podcasters, and it's a solid option for anyone else who needs to record an hour or less of high-quality audio at a time.
On the other hand, if you just need to record simple voice memos, go with an earlier model, such as the Griffin iTalk for iPod Voice Recorder or the Belkin iPod Voice Recorder, which record at a lower quality and don't require as much processing power. Or, if you want to record high-quality audio for longer than the approximate hour of battery life the TuneTalk/video iPod combination offers, check out the stand-alone Edirol R-1; it records for longer and offers an optional battery pack.