We bought a Malibu LS in 2004 and when it works it is great. We have gotten highway mileage anywhere from 35-38 mpg on several cross country trips, and it has nice acceleration when needed. We had to have the steering column replaced (under warranty) and the mechanic explained that this was a common design flaw in the '04 Malibu and that we were just fortunate that we weren't doing anything dangerous when the power steering went out. Other than that and a few other maintenance (under warranty) issues, we like our Malibu and if we were in the market for another sedan we would get another Malibu (but our family is outgrowing sedans).
Highway fuel economy, power, comfort
The steering column was massively flawed and had to be replaced on many Malibus.