It may be over four years old (and be forever stuck on Android Marshmallow) but it still feels surprisingly snappy.
I used the Nexus 5 for two years - between the iPhone 4S and 6S Plus - and it served me incredibly well. Making the switch from iOS to Android wasn't too much of an issue. Okay, so a couple of apps I used were iPhone only but I found alternatives and wrote well in excess of 100,000 words on it in 2014 alone.
You use what you have available.
I currently feel as though I couldn't go back to Android again now that my workflows are so well defined, but old "Nexie" reminds me that I'd manage. It would be uncomfortable for a while as I established a new way of working but, ultimately, I'd manage.