just right, not that easy, not that hard; with a lot of stuff to do, is not perfect, cause i had some problems with AI
i put 9.5, because i had some problems, not in the difficulty, just in game failtures, on some levels.
FOR EXAMPLE: in the last mission, i died once just for falling on the water, on a video of that mission, and on other missions the AI wasnt that good, in one mission, i had to wait for someone to get in the car, but i was perfectly in possition for he to enter, but...
he just didnt come inside...
and i died once in a taxi just for the patetic driving skills of the driver...
so, it has some mistakes.
the story line was perfect, i got involved and i liked the side missions, and the manhunt stuff is great, some achievements are so difficult, but there are some that are not, so is a very equilibrated game.
gta4 is not a perfect game, but still a grate game, and for me, the best of the year!