Pretty good I should think! you may have trouble going "through" the mountain (ground) behind the antenna, depending what it contains.
A friend of mine is in a valley, surounded by flint mountains. H.F. isn't that bad, but V/UHF is really hard work.
Having a level H.F. antenna isn't really important, as the radiation bends all over the place, due to propagation.
I seem to remember someone saying G5RV's work best if the feeder is straight down, which yours is.
Probably wouldn't hurt to raise it as high as you can