I did play a bunch of the arcade game, so I knew the basic conflict. Colwyn runs around, avoiding rocks and "slayers", and there's a five-armed boomerang involved.
Turns out, the movie had bits that were better than I anticipated. Liam Neeson's in it, for example. There are some beautiful landscape shots, and the interior of the bad guy's castle is imaginative, in spite of the obvious bluescreen compositing.
When I watch movies like this, I take extra glee seeing names that became big (e.g. Neeson) after the movie. I saw the name "Freddie Jones" in the credits as a fairly big role, and I spent the entire movie waiting for Jeffrey Jones to show up. Freddie Jones played the sage old man in this movie (and Thufir Hawat in "Dune", if that helps). Jeffrey Jones was in Ferris Beuller's Day Off and Howard the Duck. He wouldn't have been out of place in this movie, probably as a lieutenant to the villain.
The one big gripe I have about the movie is that the hero has this mystical artifact, a telekenetically controlled five-armed boomerang. Sort of like the lightsaber of this mythos, in that he goes on a quest to retrieve it, and it has lore surrounding it. The old mentor (Freddie Jones) insists that the hero not use it until the right time. I guess that right time was an hour and a half into the movie, and then non stop until halfway through the fight with the villain. I'd probably go back and retrieve my magical mystical boomerang icon, but I'm not king.
I also went back and played a bit of the arcade game. I could only get three screens in, so I can't comment on the whole game, but it's an adequate Robotron clone. If you've played Tron, with the four "minigames", you'll find the structure of Krull familiar. The diagonal shots are awfully tricky to dodge, at least playing with a PC keyboard.