I bought a '05 s40i and so far here's what I hate about it. First of all, it's a good thing that Volvos have so many safety features because the car has the biggest blind spots of any car I've driven. Also if you simply roll down the passenger window and drive any faster than maybe 50 MPH, there is this horrible vibration due to the cars aerodynamics that is totally unbearable. Has anyone else noticed these things.

 

Yeah it does have huge pillars between the front and rear seats, and the rear headrests do take out a large chunk of visibility but these are both for safety. In a side collision, you will be glad that those were so thick. The headrests stops your rear passengers having their necks snap in a collision, though I wish they could just slide down more easily instead of having to place them somwhere after removing them.
I'm usually too picky about temperature to keep the windows all the way down so I'm not too sure about a drag problem.
To add to your gripe list I'd say when turning off turning signals, I find them too easily turning on my opposite instead of just staying in middle position. This though is probably all of a matter of getting used to, and I just need to flick more lightly when I turn them off. Another thing would be the fact the rain sensor automaticly turns off when you remove the key from the ignition. Most would not press the button every time they start the car, so once its starts raining you have to press the rain sensor button. The whole point of rain sensing is that you don't have to waste 1 second of your valuable time to flick your wipers on. I don't know why the swedes didn't get this.
Apart from that nitpicking, its still an amazing car. Safe, stylish, and with my T5 fast as well. Considering I got it over $5,000 below sticker, I couldn't be happier with any other car close to its class.