This is not the first Archos player I have used. This 404 was bought to replace the Gmini 402cc (which is a rather nice player as well). This player features a bright 3.5" LCD screen, 30GB harddrive, photo viewer, rechargeable battery, and large buttons. Battery life is far from stellar. 12 hours for music playback and 4 hours (!) for video using the built-in screen. Unlike the previous generation of players, out of the box, this model only comes with a proprietary usb cable for both charging (very slow) and file transfer. An accessory kit (travel adapter kit) must be purchased to get the ability to charge via electrical socket. I was not used to, so was very annoyed to have to spend another $25 (best price so far) just to be able to charge quickly and have a usb passthough port. With the DVR Station accessory ($99 from www.archos.com), you can turn this player into a portable DVR.
Audio playback is pretty good through the headphone jack and not so great using the built-in speaker. The quality through the speaker is about what you would expect from a digital camera or camcorder: it's not meant to be full featured surround sound. This player will play mp3, WMA, Protected WMA, and WAV encoded files. Support for AAC and AC3 files can be purchased as an additional plug-in.
The 404 and perhaps all Generation 4 players appear to be a bit more strict about what types of avi files it will play. With the 402 I could copy over an avi without regard as to the bit rate and not worry about whether or not it will play. This model also claims to play H.264 files up to DVD resolution and AAC sound and MPEG-2 up to DVD resolution with AC3 stereo sound with an additional plug-in. Each additional plug-in is about $20 and is tied to your specific player.
File transfer requires no extra software. You can set your player to be recognized as a harddrive and drag-and-drop your files to the appropriate folder, or if you choose, you can let Windows Media Player manage your files. It is also Macintosh and Linux compatible.
Overall, I wish I had done my research a little more carefully before buying this product. I really feel that the Gmini 402 was a better player and I only "upgraded" to the 404 because I broke the 402's screen. For what it's worth, the 404 is a nice player. It will play your mp3's, it will play most of your avi's without reencoding, it has a bigger harddrive than the Gmini, it has a bigger screen, but it just seems lacking somehow. I would have gladly traded the internal speaker for a power adapter and port.