Well, by your statement of " original photo in color really wasn't very good" says a lot. Can't take a bad color photo and make it great in b&w. I don't know about lightroom, never used it. The darks vs. whites are what is throwing my eye. It's almost too defined. Making it look not very real, or fake. I love a good contrast...so I don't think its that. It is hard to say really...I may just not know the right words. There is a lot of gray...not much white. all the blacks almost look like a shadow..no real details in the blacks, that could be what is adding to the fake look, I would have thought there was detail in the cliffs, not just a solid black peak.
can you post up the color so I can see where you started from?