I'm just off this excursion and it was what I researched: free drinks, no stops, restroom on board.
Additional notes were to sit on top level for clear photos. I chose across from the stairs so I could stand up to take pictures of the other side without bothering anyone. The bench seats are facing in so you are looking over your shoulder mostly. The cars rock a lot.
The only thing I learned onboard is that the train is half the trip, scenic bus ride back. Or vice versa if you have the later excursion. Recommended experience!