Sure am. I had my 600D with me as well, and while some of the shots from it were still nice, there just didn't seem to be as much detail recoverable from shadowy areas. It feels like a tiny kids toy in my hand now compared to the 5D2 with the battery grip on. With the 5D2 I quickly found I needed to dial in +2/3 exposure compensation otherwise it underexposes all my shots. From a bit of research it seems it's pretty common. I really need to get the sensor cleaned on it too. I found a couple of the pics I took on my last trip needed a few spots removed. I'm not surprised though as I'm doing a lot of travel with work right now and I'm taking it with me each trip and wandering off into the wilderness taking shots after work. Changing lenses in rainforests, on beaches, and in paddocks is bound to let a bit of dust in. Easy enough to clean though.