This game isn't bad at all. My ten year old son loves this game. I watched him play the game, and wow, I could say the only thing bad is the trailer - it's misleading. I would suspect the game to be teen when I saw it. Then, I looked at the cover and it said: M for mature.
Now, my wife buys a lot of games for my two sons, ten and twelve and included Assassin's Creed, Left 4 Dead 2, Halo 3, Call of Duty: Modern Warfare 1 & 2 and finally Dead Rising 1 & 2. The worst game was Assassin's Creed but the one that is most appropriate is Halo. The gore in the game is very toony and my son has not been affected. I would put this game as E10+ .
The game is not as mature as you think. In DEADRISING: chop till you drop, there is a very small amount of swearing. The only time the game says anything "strong" is probably at the beginning. A good part of the game is focused around mild language.
Now the blood on the other hand is incredibly "cheesy" and nothing to be worried 'bout. If the blood means that much, then you can easily change the color and amount under options.
If you let your kids play any Tony Hawks (T rated game), I think they are ready for this.