I find it most valuable when traveling to different states/regions where I'm unfamiliar with local streams, access points, etc. Yes, you could find that data elsewhere, but last year, when we took a cross-country trip in our RV, I didn't have as much time to research areas before fishing. Generally, I only had a few hours in each state, so I thought it was a helpful tool, and it did save me some time.
If you're staying in PA, you probably don't need it.
I agree with others on the stream rating systems. I find them misleading at best. Some of the best streams I've fished in recent years have been categorized in their lowest tier.
I still need to try the OnX maps. A few months ago, they bought TroutRoutes, which I think will be rebranded as OnXFish.