Only thing missing is a Photoshopped-in star-twinkle off the camera-left incisor tooth!
Evaluating this, I think that honestly the light is a little too flat...too much fill light, not quite enough a lighting ratio. The shadow side of the face doesn't have much shadow, really, so the face does not have quite as much fullness, as much three-dimensionality, as maybe it could have. On a female, or a person with fairly wrinkled skill this lighting set-up would look better. This is a very flat lighting ratio, like 1 to 1.5...it's low in contrast, has a pretty close match in terms of highlight and shadow side. But by the same token if this subject were a woman or girl in pastel colors, this lighting would look really nice.
I think I might rotate this counter-clockwise about 1 to 1.5 degrees at the most. Tilting a man's head toward the lower shoulder implies a more masculine pose, and increasing the shoulder angle will make this appear more dynamic at a sub-conscious level. I'd like to see a bit more cloth below the bottom button on the shirt, and I think I'd darken the shirt and the bottom of the frame a little bit with a subtle edge burn in Lightroom. I think the neck looks like a minus .5 EV burn in would improve the shot quite a bit.
The issues I'm pointing out are mostly because the light is VERY CLOSE to the face, and coming in from a relatively straight angle, lighting the face fairly evenly. Lifting the main light up just a little higher would have moved the catchlight up on the eyeballs, and would have caused a little bit more shadow under the chin. You have to look very,very closely to see lighting effects; a good way to see them more-easily is to open the image in software, then pull the exposure down to Minus 3.5 EV, and see where the "brights" are...what areas are being hit by light most directly? It's subtle, but you can see that the umbrella is lighting underneath the chin, striking the neck a fair bit, and with a black short at the bottom, the neck skin is just a bit too bright...an under-chin shadow really can help keep the focus on the face. Same with a bit of shadow somewhere being cast by the nose--often but not always, a nose shadow can be a god thing.
I don't want anything said above to be construed as negative, because what you have created here is a very nice lighting effect, and overall this is a pretty surprisingly good first effort. The light is fairly even, focus is good (tip/bridge of nose is just beginning to trend ever so slightly toward OOF), and the degree of realism is very high; stubble, hair, facial texture, teeth,eyes, all look very real. I think on this particular man, eliminating the reflector fill might have looked better. Overall though, this is like an 85 score out of 100. Background wrinkles are the only real flaw; everything I have mentioned above is just minor stylistic/artistic nuance. I think for a first effort this might be the best one-person umbrella lighted portrait I have ever seen on TPF.
I think you might want to keep a good idea of how you did this, For experimentation, try moving the main light just a little bit higher, and maybe try to create a bit more of a highlight/shadow side on masculine-looking men like this guy, by reducing the fill light or feathering the light beam a bit, so it's not aimed quite so "square into" the mask of the face, but so that the light rakes across the face a little more, being interrupted by the nose, and casting a little bit of a nose shadow, and creating a bit more of an under-chin shadow.(For the record, I think it is easier to move the main light back a bit farther away that you are doing here, to avoid "lighting up" all the skin on a person so evenly...) Again, on younger people, on women or girls, or elder ladies, this lighting pattern would look very nice. I've not been C&C'ing this on the beginner scale, I've been looking at this image as if you are a professional shooter asking, "What, exactly, does this need to make it the best it can be."