Not too bad.One thing to watch for on portraits of people who wear eyeglasses is what the camera lens sees THROUGH the outside lens. In the man's individual portrait, we can see the distortion his right eyeglass lens causes. At the cheekline, his head shrinks inward, due to the effect of his eyeglass lens...if his head had been turned a bit more, that would have been avoided. This flaw does not look too bad at this small web size, but in a closer view it would look very bad. In the dual portrait, you can see the camera's view is more straight-on, and does not cause that.
These shots show how much better OCF and an umbrella looks that just ad hoc light! Good use of the wall, dropped to darkish gray...color-neutral, kind of formal and business-like. Her nose shadow looks a bit stronger than his, and SHE has kind of a more-aggressive and harder light than he does...perhaps that's okay though, but I think she looks a wee bit too hard-lighted. It's always a challenge when there's no modeling light to get the light and the subject positioned EXACTLY, shot-to-shot or when the subject changes his/her relationship to the flash.
As far as a light meter: a MUCH more-valuable tool is a "real" studio flash, that has a continuous light source as a modeling light; it can REALLY helk in avoiding eyeglass reflections and surprises in where the shadows fall, and it REALLY aids in getting the EXACT placement of the shadows from the nose and chin. A good trade off is the modeling light over the meter, if you have to choose just one...