这两种用法都有。前者强调对某人重要,后者一般是说it's important for sb (to do sth.)强调对某人做某事重要。
比如,"You must remember it, because it is very important to you." my brother said.
To be careful is important for you while you are taking exam.
追问我也是这样认为的 ,可人家书上就是说It's important for us.我真的很无语。。。
追答没关系,意思表达到了就好。咱也不是什么文学大师,死抠语法。语言最重要的功能之一就是沟通。不用太纠结。