Hi Ewan its a nice pen for a first pen and from what I can see it has a very good finish because I can see the light reflection.
I would like to make a suggestion for the next pen, you will see that yours has a deep waist, this generally comes about as a result of not wanting to turn too close to the tube. In fact you actually have a lot more material you can play with, so if you are happy with the amount of wood that you have left then you can add ornamentation such as beads and coves in top and bottom section, or you could also turn the pen down to parallel with the Bushing dimensions and make a really slimline pen, which if you use a well figured wood would show off the grain beautifully. I dont think you need to worry about your pen making skills..... its now about adding the extra dimensions.
Nice job well done.