You cannot be "run over" by the Deeprun Tram. Should you fall off the platform, the train will pass harmlessly over your head. There are ramps nearby to climb out.
While whether or not it is speedier than taking a gryphon flight is debatable, it is free, fast, and carries a scenic touch. Notably, however, if you take a gryphon flight, it will carry you to the other city on demand; if you take the tram, you must first step onto the tram, and then you'll have to step off at your destination. (If you are about to go AFK for a minute, the flight will be better for you.)
The transit time between each end is 60 seconds and remains at each stop for 12 seconds.
The Deeprun Tram takes 20 minutes to walk at 35% speed (Walking) and 7 minutes to run at 100% speed.
The Tram itself has its own loading screen, but it functions like a regular public space, and not like the party-exclusive dungeon instances. This was done to prevent having your computer load each zone between the two cities load as you pass under them. Furthermore, even though Ironforge and Stormwind are geographically North and South in relation to each other, the tram appears to run East and West on the mini map upon entering the zone.
In many official Azeroth maps, including ones in the RPG books, earlier games, Blizzard's website, and even WoW's manual, Stormwind is located along the northwestern portion of the continent of Azeroth, near the northwestern coast of "The Great Sea". Whereas Dun Morogh is located northeast of Stormwind in those maps, with Kul Tiras and other islands to the west of its western shore. In these maps, the Deeprun Tram actually passes under a very small portion of "The Great Sea", directly south of Kul Tiras and other islands.
Due to limitations of the game's engine, and because zones are roughly the same size and fit into roughly rectangular shaped area, they had to be placed next to each other for the paths to line up, this forced most of the northeastern dwarven lands west, just north of Stormwind. Even some locations are forced to overlap the world map, and exist in instanced zones, due to limitations. One example includes Alterac Valley which actually overlaps Alterac Mountain zone in its own instance, and cannot be seen on the world map. The same occurs with Arathi Basin and Warsong Gulch. The Deeprun Tram is forced to "overlap" several locations it does not actually pass under because of the same world scale limitations.
The large body of water the tram passes through is considered to be inaccessible, but does contain a few notable objects. Scattered inside the body of water is a treasure chest, a Deeprun Diver, shipwrecks, a large beast named "Nessy", a giant clam, two Naga Sirens, and a Basking Shark.
Unlike Horde zeppelins, the Deeprun Tram is not guarded by Alliance guards. It is also especially handy to Horde players wishing to get from Ironforge to Stormwind or vice versa. On PvE realms, the Deeprun Tram is neutral territory, so Horde players may stay there as long as they like once their PvP flag drops. However, because the entrances to the Tram are deeply entrenched within Stormwind and Ironforge, it may be more difficult to infiltrate than Zeppelins; you must get through an entire city first.
The goblins who run the zeppelin systems, eternally jealous of the gnomes' engineering skills, try to pass the Deeprun Tram off as a rumor and a myth to members of the Horde, who will probably never see it for themselves, as evidenced by comments made by Hin Denburg.
For Horde raiders who have just raided Ironforge, the Deeprun Tram can be useful to then raid Stormwind with an attack from inside the city.
The underwater section of the Tram is, in fact, a subterranean lake.
The Deeprun Tram was originally going to go between Stormwind and Darnassus.