Last Saturday, I broken my smartphone just want to cleat the dust on the back camera. Then I use a backup cellphone for few days. It is an interesting experience. The conclusion is cellphone is good for focusing on work and study, but it is not enough for communicating with families and friends.
Cellphone
I used the backup cellphone for around 4 days. There are several advantages, including simple to use, no need for charing everyday, good for focus. It is too simple to use that I don't know how to dial a number, since you need click into contact app and select the number at the smartphone. For the four-day use, I didn't charge the cellphone after the first full charge. The most advantage would be that you don't have to check your email, facebook, wetchat, instagram etc every few minutes, because the cellphone is not capable to do all of these.
Smartphone
Smartphone has multi-fucntions to meet your requirements, such as call and text, use emails, search on the internet, use apps. Honestly to say, I worried about how to contact my parents in China when I broken my smartphone. Because I don't know if my parents would contact for something using wechat. Another thing is I don't have to check my emails, so I sent my advisor that I broken my smartphone and can only text and call.
All in all, using smartphone is some kind of necessary to keep in touch with families and friends.