I visited this WHS in April 2017 with my wife and dog. Signage seems to have improved since the visits of previous reviewers, as there's now at least a "Welcome to the WHS" sign (two of them, in fact!).
We drove our car up to the hotel at the top of Engolasters and parked in their parking lot, before walking into the forest. It's about 90 minutes walk from here to the start of the site, and it's a very pretty trail through pine forest, over rocks and through a small tunnel as well. For most of it there are great views back to the city of Andorra La Vella.
There is a look-out at the border of the actual world heritage area from where you can see most of the valley, but since all three of us were tired we took some photos and decided to turn back. Pressing on would have required a serious downhill walk and then a serious uphill walk as well! You can see some evidence of the shepherd's huts and trails from this vantage point, albeit at quite some distance.
Overall it's not the greatest site we've been to so far, though if we'd started earlier and been fitter we might've found it more interesting!