i love my X3. i got a 2006 as a loaner when i got my wife's 2006 330xi, and drove it from Miami to Key West. i fell in love with it, and when it came time to get a new car, i opted for the X3. it could use some more power, but that's part of the trade off with such a heavy vehicle.
i don't have the sport package, and find the suspension to be perfect. it's firmer than my old pickup truck, but not harsh.
in terms of the interior, i find it to be perfectly suited to a driver. the only things that are missing are the following: dual zone climate & rear-seat A/C. since i don't sit in the passenger seat or back seat, i don't care