I got an iPhone Air as my work phone a few months ago. I figured that if I have to carry two, the second one may as well be thin. I was willing to accept the other limitations on my non-primary.
I have been presently surprised at how capable of a device it is. The battery life is surprising decent, not nearly as bad as I thought. The speaker isn't great, so headphones or earbuds are a must if you plan to do any media with it.
In retrospect, I would have been fine with an Air instead of the Pro as my main phone.