Well, not all paintings are realistic. As for the OP, I think it's decent, but as Dizfunky said, they are all leaning away, and I think this takes away from the quality.
I appreciate the fact that all the mountains lean the same way. It gives it direction and makes it abstract. Anything counter to the flow would look bogus and ruin the piece as a whole. That doesn't mean something counter to the flow can't be good it just means it wouldn't work well. It looks great, reminds me a lot of Appalachia country which hits home for me. Love the clouds too. If you're interested move the clouds lower to act as mist and color them blue. It'd be a nice touch to make them look like the Smokey mountains which, in my opinion, are the most gorgeous mountains in the world. Oh and very very slick depth. It would be perfect if you would try giving the mountains more dynamicism. Instead of making them follow a linear flow make the chain roll like a wave and make some come up short (for instance the middle row) and make the back row more distant and sporadic. This isn't to change the piece into something its not but to make the one you have look a bit better.