When Zack implies that shooting APS-C is a good as Nikon full frame, that doesn't automatically apply to Canon APS-C sensors. We're lagging behind. But when you look at other modern sensors (such as Fuji) that are being put into camera systems in which quality lenses are being specifically designed for APS-C sensors (such as Fuji), you'd be surprised at the high image quality. Modern APS-C sensors are excellent. Rather than being defensive and negative, we should become proactive and demand Canon pick up their game.
I was about to make that point about the lenses. Nearly 15 years into the digital age, neither Canon nor Nikon has bupkiss for APS lens lineups. Unless you absolutely love 18-xxx megazooms. Still no fast portrait lens. Still no fast normals. Still no fast short telephoto zooms (70-200 equivalent). Fuji and m4/3 have fleshed-out lens lineups already. And Pentax has some amazing APS format lenses. Small and sharp. Professional lenses.
What does Canon have? A bunch of idiot parrots saying "Use an L lens." Well yes, if you're using FF. But for APS format cameras, they have absolutely nothing, despite having an awesome camera in the 7D. A pro grade camera with no pro grade lenses. Lovely.
I'm probably going to move to the Fuji or a M4/3 at some point. Not that I don't love my Mk III and high end lenses. But at some point, you get tired of lugging around heavy gear. I have a great assistant, for now. Once these smaller formats catch up -- and they will -- the FF format will look like a dinosaur. N and C have had a huge head start, but they've been resting on their laurels. Shame on them.