Pros: Full range FM transmitter. There are more options than my radio will tune to, so you will definitely be able to find a station that works.
Allows me to play my MP3s in a truck with a broken tape deck and no CD player.
Works with USB drives or SD media.
Reads SDHC Cards and Micro SDHC cards with a microSD to standard SD adapter. (Comes with many micro SD brands).
The remote is handy for skipping songs, making it easier to change songs with when driving.

Cons: The SD reader occasionally looses contact with the card. Just ejecting the card and putting it back in works to fix this. I now use it with a USB stick though since I use my SD cards in other devices.
The cable that comes with it is short, so if you want to use it with your mp3 player or other devices make sure that you have some place to sit the device near your car's cigarette plug or buy a longer cable. (note that one end of the cable is 2.5mm, not the 3.5mm that is the standard for most headphones. This means if you want a longer cable, you would have to buy a special cable or 2.5mm to 3.5mm adapter).

Other Thoughts: I bought two of them. Both are still working and they do exactly what I need them to do.
It would be nice if it recognized folders or play lists, but I tend to use it in shuffle mode anyway so maybe this doesn't matter.
The way it organizes music is strange. It seems to pick up the artist tag and organize by that. I have about 1200 songs on it and the songs are grouped by artist. If I only have one album by that artist they will even be in order, but if you have more than one album it seems like it shuffles the songs, but still keeps them in artist order if that makes sense.
It does have stereo output. There were a few other comments on this that made me wonder when I was buying it.
Sound quality will only be as good as your radio. (It sounds better in my car which is newer than my truck which is older).
I bought two. One came with a spare fuse, one did not. I found this a little odd, but I haven't needed the spare fuse, so I don't think it matters.

Bottomline: It's a good device and is cheaper than buying a new radio for your vehicle. Especially if you already have a USB stick or SD card to use with it.
It recognized all the music I put on it.
It has multiple options for input so it is very flexible about what you can plug into it.
It will only read from one input source at a time. So don't think you can put in an 8GB SD and an 8GB USB and get 16GB of music at once. You will have to switch them and only use one input at a time.
It doesn't support play lists or allow you to search, but it did seem to group the items by artist, so if you remember the numbers you can punch in the number of the song you want to hear.

Pros: Great product! The best upgrade from the previous FM transmitter I had is that you don't have to use any cords (although you receive one if you do want to use it).
Comes with built-in mp3-player, which means you don't need to have an mp3 player or iPod additionally to the FM transmitter, just USB drive or SD card.

Cons: Doesn't seem to have to option to skip directories.
Weird last song played things:
1. Remembers last song played, but not the location where it stopped, starts from the beginning of the song - no big deal.
2. Does not remember the last song played if I first start the car and then plug in the USB drive - solution: just plug in the USB drive before you start the car.

Other Thoughts:

Bottomline: Definitely worth the money. I own it only about 10 days now, so far, it does the job.

Pros: Works off of SD card or thumb drives. Has a large selection of channels to tune to. I was actually surprised it works as well as it does. I fit a ton of songs onto an SD card and it works pretty good. It has a nice flexible joint to it too.

Cons: Can't tune to 100% clarity. Sometimes there's a light buzz. The interface itself is a bit confusing and it comes with very few instructions. When set to random it seems to enjoy playing a few of the songs I have over an over. lol.

Other Thoughts:

Bottomline: Works better than I thought it would!

Pros: -Full range transmitter! you can choose whatever frequency you want.
-The transmitter seems to be powerfull. Overrides big local stations if you set it to their frequency.
-Shows songname and other usefull information in the display.
-Takes SD
-Works on both 12V and 24V (according to packing!)
-Comes with a remote controller
-The singal is pretty clean in the lower frequencies, above 100mhz it "hums" a little.
-The price

Cons: - mp3s restart when ignition is used
- no fast forward/backward
- changing volume is not well implemented
- 3.5 jack input is NOT standards. don't lose the cab

Other Thoughts: For $11 what do you want? It at least has a screen to show the title playing. It loads music very quick and starts playing right away. It even remembers the song last played and the FM frequency last used. That's very handy. It doesn't remember the volume level though and it's default tends to overmodulate.

Bottomline: Still great to pop into my car to listen to tracks.