There are probably two major barriers to entry on Warcraft, and characters with names like Gul'dan, Khadgar, and Medivh only represent one of them; the other one, and perhaps the bigger of the two hurdles, is that there's just too much here to fit into a two-hour movie.
The opening is breakneck, throwing characters, locations, and names around with enthusiastic abandon, but without really introducing any of them. It's a shame, because there are some valiant attempts at character work scattered throughout, but a huge amount of development feels missing - it often feels like they've left fast-forward on for long sections, as we whizz through (or, more often, past) the "craft" part for the sake of getting to the "war".
Full disclosure: I was a big WoW player for about seven or eight years, from just after launch in 2007 to about midway through Cataclysm. In that time, I was something of a lore fiend, and went so far as to read several of the tie-in novels. The point being, I already had some idea of what the plot of Warcraft was going to be before I even got close to booking a ticket.
I have no idea how confusing this film must be for someone without that reference point.
