Hi, now THAT is an interesting Q/post and not often to be seen. But I´ll try to explain a bit: there are 2 hourly EC trains on this line, they should run via Nove Zamky-Sturovo (last stop in SK)-Szob (1st in HU)-then east side of Dunav (Danube for you), in fact the lesser part-to reach Bp. Most trains start od Prahy. The trip takes like 2h30 m.

BUT due to landslides a part of it-in HU, right along Dunav bank, line was destroyed-and trains rerouted-via longer route, some cancelled, via mostly HU-flat land, nothing to see-Hegyeshalom-Györ-Komarom-Tata-then via some low hills to Bp.The fast trains from Wien also use this line. The old line should be ready to use again this week or next week, first at reduced speed only.

As counting the normal interesting touristy sites: these lie in HU in what is called the Dunav-bend/knee (look at map-where it turns from east till south), places like Esztergom, ´historic village´-…. There is a recently renovated busy local line from Esz to Bp, but not via the scenic parts-that is done by a Volan bus (this runs all the buses anywhere in HU). There is-only mo-fri also a Volan bus Sturovo-Esztergom, mostly to connect from these EC trains-cost is quite low. And there are a very few ferries over the river between rail-side and west-side, but I dk current situation-if these are also hit due to slides and no cars.

So all in all there is very little to see/do in between these 2 directly along the rails-and the medium interest places are off the line-so require effort and money to get there.

If you want to spend the day and depending on what else you visit-I would say: take early train to Wien-have a look-and use direct train late afternoon to get to Bp. That is off-route but likely more rewarding. No RES mandatory for any of these trains-but can do if the fears of no seats are too great.

As for HU: do not just stop in Bp-visit more, my favorite is Szeged in the far south, near what once was Yugoslavija, now Serbije. Famous for its PICK salami too