Pros Crispy clear sound in the mid frequency range. Very crisp sound in the highest frequencies.
Cons The mid range of the tweeter (higher than human voice,lower than hiss) are way too loud and aggressive. Totally pushing the rest of the sound image to the background Listening for longer periods to this set is tiring to the ears and becomes annoying.
Summary It is is still a good buy, if you are willing to fiddle with the system. First of all, use an exeternal amp. The resistance of the speakers is only 2 Ohm, instead of the regular 4. That makes the speakers go louder, but also puts a much bigger strain on your in-radio amplifier. Most will not be up to the task, causing all kinds of rumbles in the sound.
Second, use a low pass filter, in order to prevent sub frequencys being fed into the speakers. I have 13 cm (small) mid speakers, and they distort very quickly at the lowest levels, even with low listening volume. With the low pass filter, this problem is solved. Also, it frees up capacity from the amp so that the over all sound quality improves. In order to get low / bass you need to use a (small) subwoofer.
Secondly, you could build an extra filter for the tweeter, to get the volume more in line with the mids. It only takes 2 resistor of less than a dollar. I used a 3.3 Ohm in serie, and a 2.2 parrallel. This improves the quality of the sound dramatically without cutting off the top frequencys. I estimate that it takes 8 to 12 DB off the tweeter volume. I am thinking about lowering it even more. Mind you, these are huge correction values.
I think for speakers with the name infinity on it, a make that became famous for it's detailed sound in high frequencys using electrostatic drivers thus painting a clear 3d sound image, it should not be necessary to manually add filters in order to get the over all sound frequency ranges acceptable. The filter in itself is of high quality, it just takes different vaues of some components in there. Even when the ratio's are corrected, I think the tweeter is souns a bit cheap metallic, e.g. compared to Focal, or the top line tweeters of Infinity itself. Me myself, I'm saving up to buy Focal speakers for the front of my car now and I will move these Infinitys to the back.
Over all, ot bad speakers, but add a bit of your budget and you can get much much better without having to build your own extra correctional filter.