I had a G6 V6 for a few weeks while my GTP was being fixed. It was a pretty base car, but I was rather surprised at how nice it was. The interior of a base G6 makes the more expensive 97-03 GP's interior feel cheap, though the seats in a GP are loads more comfortable than the G6's.
I was getting 28-29 MPG in that thing going to work everyday. Compare that to 24 in the GTP, taking the same route and driving the same speed.
That V6 would still get up and go, and you can hear it too. It's a somewhat docile looking car, but don't let that fool you. It's has a nice ride, very quiet inside, and of course it manuevers way better than a GP.
I don't really have anything bad to say about it, except the gauges are kinda funky and distractingly shiny what with the silver dash pieces everywhere. I did get blinded a few times.
Looks like a good car, though. I haven't seen any with high mileage yet, so I don't know how they hold up in the long run, if you plan on keeping it for awhile.