I finished the game, and I'd give it an 8 or 8.5.
The pre-RC parts are 9/9.5. The latter half brings it down.
Part of the problem is that the game doesn't feel like I, as a player, am building off of knowledge and skill that came before since the gameplay and level designs change so often. Plus, the inventiveness and novelty of things in the first half (the Girl's design, the zombie-to-zombie interactions, the wild swing in gameplay style from Grace to Leon, etc.) drops off in the latter half.
For a strained analogy, this game is like getting a Greatest Hits album from an electronic artist, where every song is a decent remix of songs I like. It's not coherent or that original as an album, but it is good fan service.