OK, you requested a critique, so here goes... First of all, Mr. Tennant is recognizable, so congratulations on that, he has a very difficult face to draw!
The main issue I can see is his left eye, where you shied away a bit from defining it clearly (or used the erazer too often) - it is lacking the reflection, which makes it look blind and lifeless. I can see a couple of harsh white lines where I think you scratched the paper - if you make the first drawing with a very hard pencil, try not to press as hard and maybe use the side of the lead rather than the tip to avoid fine white lines in an otherwise dark area. You could improve the overall impression of the picture a lot if you just pushed the values a little, his eyes should be just as dark as the shadow on his suit, and there is too little variation in his hair. The line where his lips meet should also be darker than his bottom lip.
A couple of details could improve the likeness a bit, but they are really minor. His nose (which is especially difficult to draw, I know) is actually a bit longer - if I'm indeed looking at the same reference picture you used, the tip reaches the line of his cheek, and the nostril could be a bit longer, too, but less deep. His left eyebrow extends a bit further towards the nose, and the line of his forehead should be tilted back a tiny bit.
As I said, those are minor things, you've got the overall proportions of the face down nicely, so please don't be discouraged by my nitpicking!