I use the H4 for almost a year and I am fully satisfied. Since August 2007 the firmware has changed considerably and opens up new possibilities for this device. Do not hesitate to update .... there have less than 10 mm for a new camera! just load the file. bin at the root of your memory card, then you must turn on the H4 holding the menu down to say yes to delete files ... in less than a minute the update is "complete" and you turn on the H4!
The major changes:

Support for SDHC cards over 4GB

could display large for readability

a battery indicator (FINALLY!), and the remaining recording time.

an ability to create separate files of the same record several hours.

Adding a low pass filter to remove wind noise and pop

Adding a function to encode WAV files to MP3

addition of a Mono Mix function that can record two track with a microphone plugged into input 1 or 2 (H4 finally to a true function as a tool for interviewing!

Adding an auto-save feature when the input signal exceeds a certain level (the voice-triggered recording!)

Adding a function to automatically increase the logging level to its maximum

support reading USB cards on OS X v10.5 (Leopard).

solved slows down the rendering of distortion when the gain is set to High or Mid 4-track mode.

These are the new versions 2.0 and 2.1 so if you have a version 1.2!!
Good deal to do with opportunity, if the previous owner does not know the firmware update! and nine should not hesitate to buy in the U.S. (given the Coptic dollar) tatnt worse for the warranty and the AC adapter 110 V!

The link to download the version 2.20 can be found here:
https://www.zoom.co.jp/english/download/software/h4.php
bottom of the page select the file to download depending on the version of departure.