David Tennant's Tenth Doctor shows Martha Jones his screwdriver in this cosplay and they both find it very interesting indeed. What? He does! They do!
Silliness aside, I like this cosplay it captures the characters without being too slavish to every tiny detail. It's been well posed in a way that fits the two characters and the photograph is effectively composed. Unfortunately I often see what is good cosplay spoiled (for online presentation) by a poorly composed photograph.