I have an 05 w/ a 3.5. Has 172,XXX mi on it, lol. Bought it cheap w/ 149,XXX earlier this year. The motor is just about the easiest dang thing in the world to maintain. Changed the plugs, wires, air filter, switched to synthetic oil, new tires all around since then. Doesn't take much to keep the car running, honestly. Next up to be changed on the motor are the oxygen sensors.
Here's a couple issues the 05's have, not sure if 06's share them..
1)The running lights can get hot and scorch the interior of the housings. Mine actually burned a hole through the tops of orange bulb covers. Change them to LED's.
2)The intermediary steering shaft is janky. Causes a slight knock/tick/bump when turning the wheel across the straight ahead position from either direction. I had it replaced for free when i bought the car. It still has a slight tick, but the replacement shaft is much better than the original.
Other than basic tune-ups, its a very easy car to care for.