We went to see UP last night. Two thumbs UP. Way UP. Truly enjoyed it. It was a little edgier than most Pixar. It is rated PG. Realisticish blood. Someone dies (off-screen). I still recommend it. I would skip the 3D (yes, we saw it that way) - it isn't necessary to enjoy the film, I personally find 3D glasses distracting at best.
This is one animated movie that will appeal to older audiences just as much as it will to kids. I loved the scene where two old guys are fighting (sword against cane) and they both throw out their backs. Priceless.
Go see it.