It's a fairly capable GPS, if it's working correctly, of course.
I have its slightly newer cousin, the Vista HCX, which supposedly has a more sensitive receiver. I get and keep good sat' locks under heavy canopy, but it can take a while if it's moved a reasonable distance while powered OFF.

As the Vista has been discontinued, is it safe to assume that you got it used?
Were you able to get a sat' fix while at home?
Did you only power ON the Vista after you got into the woods?
Did you find the Satellite screen that shows the sat's from which it is receiving information and, if so, how many showed solid bars?
Did you have maps [preloaded] for the area you were in?