Summary: This was one of the only decks that I found at the time that has both SD & front USB - this was my #1 criteria in choosing this deck. There are several with one or the other, but for me, the advantage of having both is that I can put some of my favorite music on the SD (which is hidden behind the face plate) & leave it in all the time, and remove the USB drive more often to swap out music / drives.
Drives Used:
2GB / 4GB USB drive
2GB Creative MuVo (through USB)
2GB SD
6GB iPod Mini (through USB - without additional iPod adapter)
I am using this almost exclusively with SD & USB - I haven't bothered to play CDs at all so far. There is really no need if you have large enough USB / SD drives. I will probably use MP3 CDs some, but I may not use audio CDs at all.
One of the biggest selling points for me was the ease in which you can browse MP3s. The interface to the SD / USB is good - it will navigate through folders with one set of buttons, and navigate through tracks with the other (through both the faceplate & remote). When browsing folders, it will briefly show the folder name, then switch to show the ID3 tag after the track starts playing, which is very nice. Although there are not many buttons on the face or the remote, it is still fairly easy to do most basic functions. The display is large enough to show plenty of information (ID3 tags, menus, etc), which is a nice improvement over the lower lines (e.g. KDG-720/820).
This will work with iPods through USB without the additional adapter, but the file storage method that is inherently used by the iPod does not lend itself to this type of interface. Therefore it is difficult (if not impossible) to use the deck to browse for songs on an iPod without the adapter.
I was initially concerned about the size of drives supported - the user manual lists a limit of 512MB SD & 4GB USB. However, this is not correct, as my 2GB SD works flawlessly. I haven't tested a standard USB flash drive larger than 4GB, but it did recognize the 6GB iPod (despite the interface issues listed above). It takes a few seconds on start-up to read the files from the USB / SD (this is probably dependent on the speed of the drive), but it isn't bad at all in my experience.
This deck has a lot of EQ & X-over settings that I was unaware of when I purchased this. In addition to the 9-band graphic EQ (which is a big plus over standard "bass/treble" adjustments), it has adjustable X-over settings for front, rear, and sub. You have the ability to set both the cutoff frequency and the slope. I am still using the X-overs in my amps for now, but I will probably switch to the X-overs in the deck in the future. I haven't tested these functions enough at this point to comment on the quality, but the features are nice.
So far, I am extremely pleased with this deck - the negative points are very minor. It would be nice if it would directly support iPod without an additional adapter, but I knew of this limitation before-hand, so I can't really count this as a negative.
Additionally, the sensitivity to the remote is a little low - I have to make sure I am pointing the remote toward the receiver, or it will not pick up the signal. I have always noticed this with remotes that use "coin" batteries - the only car CD remote that I did not have this issue with took 2 AAA's, and was bulky. This is very logical though - the remote has to be low-power, or the coin-battery would not last. This issue is not really a problem, and is certainly not limited to this deck. The remote is very nice overall - the buttons are easy to recognize with your fingers & are easy to press.
I would definitely recommend this, and I am considering a 2nd one for my wife's car.