Wow, what a modern classic this is. I love the guitar part to this. That intro is very lush, distinctive and down right groovy.
The song is tuned (from low to high) E,A,D,E,B,E which is a little unusual but just goes to show how Ed Sheeran thinks outside the box with his sophisticated guitar playing.
The chords are relatively simple due to the tuning of the song, but if you are like most players who are learning this you may want a little more help getting faster chord changes.