They are definitely nice. I went with a friend of mine last weekend to test an S4, A6, and S3. The S3 was super small so that was out, the others were nice. Once thing I couldn't get over was how distracting and cumbersome the infotainment was on the models we tested (they were used). I can't see how people scroll through all the menu options to change everything while they are driving. Obviously neither of us were proficient with the system, but it still seemed extremely distracting.
It made me glad that my BMW does not have I-Drive.