Is the Glacier Express worth it?

You’ll hear people with both opinions. “Worth it” is very subjective and personal on most topics.

The faster train may take more long tunnels through the mountains vs going up and over some of the passes. Does it add hours, or days to your trip? How much time do you have at your next destination? Would you be doing something else “worthwhile” with the time you save by taking the faster train? There are regional trains that take the same route without the more expensive Glacier Express train cars, if price is a concern.

How much time do you have for the journey to Austria? As noted above, the fast train will use tunnels under the Alps with no scenery. And no snow capped peaks once you depart Visp. Take a look at this rail map of Switzerland, and you will see that the Glacier Express route from Zermatt as far as Chur ( not to St. Moritz) makes a diagonal across Switzerland toward Austria that might make sense if you want scenery.

https://www.swissrailways.com/sites/default/files/sts-gb-m-15-web_vorlage_0.pdf

The fast train goes from Zermatt to Visp and then to Zurich via a deep tunnel. The journey to Salzburg on this route takes around 9 hours. Personally I would choose a scenic route avoiding the long deep tunnel, and plan an overnight on the way.

What are your plans for Zermatt in late April? That is definitely low season there.

The fastest way from Zermatt to Salzburg is 8 3/4 hours and has a lot of changes (4) and goes via Munich, so will have minimum mountain scenery. The fewest changes (2) is via Zurich and takes 9 1/2 hours. The nominal, undiscounted ticket cost is 231 CH. Using the Glacier Express also has 2 changes (Chur and Buchs), takes 11 1/4 hours, and has a nominal ticket cost of 214 CHF. You have to add the reservation fee to that. My opinion, take the Glacier Express.

You can still take the non-premium regional trains on the same route as the GE - Brig to Chur - can you not?

As a Swiss I'd trade a day in Zermatt for a day on the Glacier Express....

But the OP wants to go from Zermatt to Salzburg, and it is an all day journey. The choice is long day with lots of changes and minimal scenery, or a very long day day with minimal changes and excellent scenery.

Given that the "normal" route via Zürich already takes so long, spending an extra two hours to go via the Glacier Express to Chur, then head to Sargans for the train to Austria, is probably worth it. 9 hours, 11 hours... At some point it makes no difference 😅

Thank you for all your ideas. I think we will settle in for the GE to Chur, then on to Sarans to Salzburg.