I'd avoid it like the plague. I've got a 2002 with 41K miles on it and in the last year I've had to repair the power window and get the BCM replaced. At the moment I'm looking at a leak somewhere in the radiator, reservoir I think, and a faulty thermostat that plays hell with the AC.
You can get much better for $6000.
See the attached file; Buick is rated the No. 1 most dependable brand by JD Power last week.