As for me, students shouldn't use their mobiles in class. It's something which distract students.

On the one hand , using mobile , when the teacher accept it, for search informations for a projet or somethings we don't understand , in this context i think it's a great idea.

On the other hand , the teacher can help us if we are in difficult, it's most an excuse for playing a game or talking with their friends by internet because it's borring for many students to listening in class and do nothing.

For instance , in a teamwork in which one we can use mobile , several students of the team don't do the work and prefere doing other things most diverting.

However , I continue to thinking it's not a good idea but i understand the fact that can be usefull in some circumstances.

To conclude , generally it's just doesn't help us and it's most distracting us.