Black-and-white imaging is tricky - if it's done well, it looks amazing; but if it's done poorly it looks awful.
So what's the key to a good one? Well, it's right there in the name - black and white.
The name of the craft is not "Shades-of-dark-grey-and-light-grey photography". It's "Black-and-white photography".
For a B-W photo to smack the viewer in the face, it needs to have plenty of blacks and whites. Any area of significant detail without a black and a white in it somewhere is flat, dull, and uninspiring. The photo needs plenty of contrast, not only globally, but in all the detail.
Let's take a look ...
Here's a snap, desaturated. Flat, right?
Here it is with contrast improved globally. Now it has at least one area of black and one area of white in it. Better.
Now it's had the works - plenty of selective enhancement to create plenty of contrast. Much better!
Now I've pushed the boundaries, searching for that really stark effect. This may not be to everyone's taste ...
... but you can't deny it's much more eye-catching than where it began:
See what I'm talking about? Plenty of areas of black, and plenty of areas of white. That's the key.
Let's look at another. Here's the photo, desaturated. Not very inspiring.
Now, with global adjustment. Slightly better, but not much.
Now with selective adjustments to find plenty of local contrast. Looking good!
Finally, with a moderately aggressive S-curve for the strongest effect.
So, when you are evaluating your next black-and-white photo, take a frank look and ask yourself "what's boring about this photo?" It might be a bland background, or some dull clothing, or the whole darn image! I guarantee that if you improve contrast to create blacks and whites, it will look much more exciting.