I did find the engine on the GM web site. Yes, the 3.5L engine is an OHV engine, and the 3.6 is a DOHC with VVT and variable intake, all aluminum.
I drove the 3.6L version of the car and the engine is very responsive, the 6 speed transmission is nice, but there was a lot of torque steer. I have not driven a lot of FWD cars, but when I drove the new VW's I could not feel any torque steer. I thought the car mfg's had resolved most of the torque steer issues? All in all I think the car looks nice, the fron dashboard is nice, but there are a couple things that bugged me. The door panels wer just one solid piece of stamped plastic. They were so ugly. I know that is a strange thing to worry about, but I was just surprised that they could be so ugly on a car that otherwise, looked very nice. Also, the carpet looked really cheap. Anyway, it was overall pretty nice. I was particularly impressed with the looks of the dashboard, since GM dashboards are usually sooooo ugly.