Mobile phones are purchased for mainly two reasons, texting or calling.
The rest of the functions installed in the phone are just accessories to enhance its attraction. If I ask you which function of mobile phone you constantly use and which one is more important? Will it be sending and receiving text messages or making voice to voice phone calls?
In my opinion, text messaging is a wonderful technology and is very convenient in most situations. Texting is cheap, fast and it gets straight to the point, allowing both end users to spend as much time and energy they choose on messaging, even if that means to ignore it completely. When you phone someone, you are demanding their attention and time. When you text you are saying "I'm thinking of you, but I know you have a life."
It's definitely better to call when you wish to have a conversation and discussion. However, I feel that having too long of a conversation over a text is impersonal. I say this because there are times and situations wherein texting is better than calling and there are situations wherein calling is much more appropriate and appreciated rather than just texting.
For instance conveying the same message to group of people like passing some piece of information, texting is obviously the best choice. But for conveying important and personal information requires personal touch and should be done through calling. Perhaps breaking up with your boyfriend or telling a person you love him, texting is not appropriate. The choice is yours; should you be texting or calling?