The thing with in-walls is that, no matter how well they are designed, a lot of how they sound has to do with the wall they are placed in. The wall becomes an extension of the speaker's cabinet and will resonate, to some degree, with it.
In-wall home speakers are similar to in-door car speakers. I've heard some really bad car speakers (like the ones in the Mitsubishi Galant I'm renting) that color the music something awful. They make the Bose speakers in my own car (Nissan Maxima) sound like gold.
Now I'm going to go off on a slight tangent. I'm on a business trip and the rental car I have only has a CD player. I brought a tape adapter with my iPod, so it's pretty much useless. I had to buy some CDs (Jack Johnson, Nick Cave, Daniel Lanois) to tide me over because the radio stations in Southern California suck monkey butt.
I'm listening to the CDs in the car and the content itself is good, but the car really butchers the audio. I can't wait to get home and throw the CDs into my home system (M22s, SVS sub) and hear them as they were meant to be heard.
