That looks like a neat system, but do remember that low power FM transmitters like these have a limited number of freqs and will be overpowered by a broadcast signal on the channel or one up/down.
If you're in a rural or semi-rural area, this will work awesome. If you're in a major advertising market, you may not be able to get a signal at all. Also take this into account if you plan to use it for traveling. Driving through Dallas or LA will probably disable the system entirely by jamming every available freq, and you may need to find a new frequency every few hundred miles as station coverage changes.
This technology really hasn't changed in the last 20 years, because the FCC limits the wattage of the transmitter for this type of device.
If you want to know if this will work for you, go to your car radio and test the very bottom of your FM band, around 87.5 to 88.9. If you can find a frequency in that range that is white noise, then you're good. If there's nothing on a freq, but you're hearing some bleed from a nearby station (like you're hearing 88.3 when you're at 88.5), or if you're hearing a faint signal, then you may or may not be okay, and your sound quality when using the device might well depend on uncontrollable factors like cloud cover.
Bottom line is if you have an aux port on your radio, you don't need or want this. An MP3 player will have as much or more storage, better sound quality by far, and require less tinkering. If you don't have an aux port, then this could be a good all-in-one solution, and it does have the side effect of turning your 12v power outlet into a USB port, which might be useful on its own.