My answer to this question would reluctantly have to be yes, but with stipulations as well as being very dependant on the generation the user is from as well.
I use a smartphone daily for my job. I use it for email, text messages, web browsing, checking helpdesk tickets and even managing our Windows Server environment. I am 36. I believe myself to be fairly well spoken as well as well written. I have common sense for the most part and I can read a map perfectly.
From another aspect, I also work with a wide range of young adults in my field. I have seen a great deal of these young people's writing skills, and I must say that what they mean vs. what they write is very disturbing. Texting acronyms have started to take over the english language for many young people to the point where they can't spell normal words correctly anymore.
Somewhat recently, I actually had a student send me an email explaing an issue that we had that literally read:
"Sry about teh insedent at wrk. I rly tryed to git it sorted. Pls let me no if its alrite now."
Now that snippet was just a little piece of the disaster that this person made of the english language. It was a very dark moment for me.
I can honestly say that over-using these devices, especially if you have lazy tendancies, will only magify those types of issues. The age group that I notice this type of behavior in ranges from 18 - 24.
This is just my opinion from experiences that I have had with numerous people from many different age groups, so take it with a grain of salt.