The more I look at it the more I think something needs to happen with the left branch that is slightly vertical.

So pretty. Did you get the look by purely pruning or did you have to train the branches at all? If I want the left branch on mine to come down, would staking and tying it lower for the season do the trick? Or am I stuck with the shape?

No tying or staking involved in my case. I just cut out all the inside and lower branches where they begin, leaving a thin umbrella shape.
I get the feeling you want your maple to look symmetrical. Nothing wrong in that. You can prune the 'offending' branch off where it begins anytime to get that look. Just leave no short stubs or cuts at the ends of the branches. You're not stuck with it's present shape by any means.
My preference is for asymmetrical trees, preferable the windswept look. Visually more interesting in my mind's eye.
I have a lot of Japanese maples and I'm doing a lot of pruning now. They're really growing fast. With adequate water they will have another growing flush later in the summer.
Mike

Other than saying I wouldn't consider pruning anything for at least season, I agree with Mike. I tend not to be very inclined to do much pruning on JM's - I like to let them develop naturally if possible - but when I do, it's to enhance the form, rather than control it. Pretty much what Mike has demonstrated so well in his photos :-)

So I'd wait and see how it does this year. You can get the more upward growing branch to bend down simply by weighting it. Tie a rock to the branch using a soft garden tying material. I use a stretchy plastic green tape I buy at my garden center for tying up clematis and tomatoes, etc. Size the rock (not too big) so that the branch just bends to the degree or level you want. By the end of the season, it should stay in that position. I think leaving this branch in place (not removing it) gives the tree balance. Not exactly symmetrical but not one-sided.

Thanks for all the helpful advice. I pulled down the branch and tied it to an extra stake I had... I like the shape much better. I also found a hitchhiker when I planted it! Just turned into the pupa stage.