I agree with what most have said here. I hate the 3 hatch's lines. The 3 sedan's lines are great, though. The p5's lines are great, but I'm not a huge fan of the sedan/msp's. So I guess it matches there lol.
From interior perspective, in the 3 I felt like I was sitting in a rich man's car. In the P5 I felt more like I was in a driver's car. The gauges on the 3 were too big, and I hate that huge tach and tunnels. I also don't like the dash cd player. On the other hand, I think some parts of the P5's interior could be a little better as well, such as a HU that could decode mp3 files.
And finally, in the actual driving of the car, while the P5 does have low power compared to the 3, I find it always has enough for me. And I'm driving an auto. Of course I'm also getting a header to add some hp, but I'm not looking to do anything drastic like turbo. The 3's faster, yes, but like others have also pointed out, you don't feel what the car's feeling. In short, P5 = driver's car, 3 = luxury driver on a budget
Oh, and I like the looks of the 6 wagon as well... as long as it has the appearance package. The only major down of the 6 wagon is the interior knobs are hard to read during daytime with the red led on silver. But that can always be fixed ;-)
LZ