I took my 5 year old daughter, 9 year old son and 11 year old daughter to see this. I coached the 5 year old a lot before we went, because I was concerned that it might be too scary for her, but it wasn't at all. The Bogeyman is scary, and the idea that he turns happy dreams into nightmares is pretty, well, nightmarish. But in the end (as the 5 yo told me herself), he isn't that scary because he is wracked by self-doubt and loneliness. You just can't be too scared of a pathetic bad guy. So she was fine with it. The 9 yo really liked it, enjoying the action and the idea and the wisecracks. The 11 yo enjoyed it while it was playing, but afterwards was a bit more ambivalent.
As for mom? I really enjoyed it. The settings and characters were beautiful and fun, and the premise was nifty. The plot is somewhat flimsy, and not that well-executed, but the characters were fun enough, and the animation beautiful enough, so that in the end I didn't care. My favorite parts were enjoying Alec Baldwin playing a tattooed (one forearm says "Naughty" and one says "Nice") Santa and Hugh Jackman an Outback Easter Bunny. I'm glad we went. A little coaching for a 5 yo with older sibs should be all that's needed. It's too scary for toddlers or younger preschoolers, and by the time a kid hits the tweens, it might be a little boring.