Lots of people do make the visit to Jungfraujoch. Its worth is totally up to you. It's expensive and super crowded especially during high tourist season. I've been several times so the "wow" factor is no longer there for me. Schilthorn is very nice, included with STP, doesn't take the better part of a day and gives you great views as well as time to do other things on your itinerary.
You can read many reviews of the Jungfraujoch on TripAdvisor. People seem to love it. But despite having spent many many weeks in Switzerland, and going to Klein Scheidegg half a dozen times, I have never done been nor felt sad not to have done it.
I think the appeal lies in the height of the views (which I understand) and the chance to experience snow for people who have not done so. Downside is that it is the opposite of mountains for me. Lots of people. And of course, the complexity of the construction means a high price.
I find that the most memorable mountain views are not always where you expect them to be. Make sure you find some time to access moments of solitude in the mountains rather than just “doing the sights”.