Eeeeh. It's a little targeted.
And not really compelling or fun. I've seen people with suggestions for UA that is stuff like "10% production bonus" or "+25% great person rate." Most of the UA need to be stuff that is more interesting than this. Something that, in general, adds a different dynamic to playing that Civ. The most borderline case I would see is the Egyptian UA, but I really like wonders a lot, so I think it's pretty great.
I do agree though that Washington's UA is very lackluster from a gameplay standpoint, mostly because buying tiles is very rarely that big of a deal (the only time I've bought tiles was when I needed a resource quickly, or I needed to block an opponent from getting that tile quickly. That doesn't happen very often), and +1 Sight to Military Units can be nice, but simply doesn't really effect the way you play the Civ.
Thematically, I think the UA is very nicely suited to America. From a gameplay standpoint, I think it needs improvement to make America more interesting.
This also isn't helped by the fact that the fast technology rate in Civ 5 also makes the Flying Fortress sort of negligible, since the Stealth Bomber is so absolutely, billions of times better than it.
Also, musketmen are not a unit I get much use out of, (especially since you can't promote to them, you have to go Longswordsmen/Pike men -> Riflemen), so while the Minutemen have a nice bonus ability, the only reason they're not mostly worthless is that you can promote Minutemen and keep the promotion.