Firstly, perhaps (hopefully) in response to the previous reviewer's experience, there were a number of notices in the car park when we visited, warning visitors not to leave valuables in their cars as there was a risk that they may be stolen.
Unfortunately, we clearly didn't do our research properly, because the 'house' of the Vista House was closed and we learnt from another visitor that, at the moment, it is only open Friday through Monday so, if you want to go inside (and I can't tell you what there is inside, because we didn't get to go in!) you need to pick your day accordingly.
Despite that, it is worth it for the 180 views of the river and gorge. You can see for miles, even on an overcast and rather hazy day. Parking is limited though.
You really shouldn't do this drive without stopping here.