Yes it is 100% safe to sync your phone with sky drive . specially memory is verry important to you . it is also helpfull when you buy a new phone you can save photo in sky drive and save your photos and video to your new phone also u can sync your stuff from your pc also . so you can acess your stuff any ware without pc . one grate thing of onedrive is you can use also for contact and email sync
helpfull for busness and student for save thair work it also sync and store your document like word exel and ppt also and it can be acces by app and also from website
concluson: best drive usefull for student and buseness