Though manga is following novels more closely, the artwork, in my opinion, is a great turn off there.
Since i am not a great loli lover all characters look too childish in the manga for me (8-10 year olds) plus the whole design is not suited for serious scenes, it is alright at the beginning where it is moslt comedy but when the serious stuff begins with
It doesnt look like they can handle it so well with such childish artwork.
So I would still recommend you to try the novels instead of manga. You can find those on baka-tsuki, and you better hurry before the first translated volume in english appears as then baka-tsuki will take off their fiorst volume and you will have to buy it instead of reading for free.