Say Cheese.

Earlier I added this one to my favorites so you know I like it... But here comes the critique.
This is definitely not original, but quite well done. As you said in the description, it is just a sketch; that is why I only gave <img src="e.deviantart.net/emoticons/s/s…" width="17" height="16" alt="" title="Star!"/> <img src="e.deviantart.net/emoticons/s/s…" width="17" height="16" alt="" title="Star!"/> <img src="e.deviantart.net/emoticons/s/s…" width="17" height="16" alt="" title="Star!"/> for technique. It is a good sketch, but it does not showcase all that you are capable of doing.
There are two things that really make this a good sketch:
1. Considering how difficult this perspective is, the proportions look quite realistic.
2. The different types of shading and lines make the drawing interesting, especially the contrast between the skin and sunglasses.
Oh, and I also like the title <img src="e.deviantart.net/emoticons/b/b…" width="15" height="15" alt="" title=" (Big Grin)"/>
I think there are also two small things that could be better:
1. The ear should probably be more oval / long shaped rather than round / short shaped... if that makes sense.
2. The line showing the left side of the face / cheek area should be less harsh and more shaded in.

In conclusion, this could use some minor adjustments, but I think you should definitely turn this into a finished piece!
I hope that this has been a helpful critique.
<img src="e.deviantart.net/emoticons/h/h…" width="15" height="13" alt="" title="Heart"/> *nfaas