Priority Pass is worth it imho if you are a frequent traveller to places where either a OneWorld or StarAlliance premium membership does not get you access to local facilities. I use my PP regularly. However, they recently changed their membership policy to be multi-tiered, and unless you are their top membership, you still have to occasionally pay to use a lounge. There are several ways to get discounted membership through points or credit card schemes, so it is worth checking those options out too.