Generally a good site. Lots of mangas are available in a good quality and in a simple way. But beware of virus and malwares that are sometimes hidden between two pages of your favourite manga.
Users of smartphones must be particulary cautious about this site and try to avoid if possible.
Unsuited for children. If I write "Umi no Misaki", "Gantz", Hentai Kamen" or "Kodomo no Jikan", I believe it will give you a clue how COMPLETE this portail is. I'm not about overprotecting our kids, I believe teens could clearly understand those things. But letting a young child playing here alone is the same as letting him playing ball on the highway.