I enjoyed Krull the first time I saw it. After rewatching it a few months ago, I still think it's got a lot of very good aspects, along with some weak aspects. The script is pretty good, with interesting mythology-building and generally good character work. It's a great-looking film, with some spectacular mountain scenery filmed in Italy and some impressively surreal set design in the Beast's fortress. James Horner gives it a rich swashbuckling score, even if he recycled some parts of it nearly verbatim in Star Trek III the following year. (And Joseph LoDuca would later pastiche it to the point of near-plagiarism for the score to one of the first Hercules: The Legendary Journeys TV movies.) Ken Marshall, who would later be Commander Eddington on Deep Space Nine, is effective as the swashbuckling hero Colwyn. I read that Marshall modeled his performance on Errol Flynn, and I could tell when I watched him. A lot of the film had an old-school swashbuckling feel to it, just dressed up with 1980s visual effects that were... well, very 1980s, but not quite up to the best of that decade, except for the beautifully animated giant crystal spider in the Widow of the Web sequence.
The film did stumble in its somewhat messy climax, and it served its female lead Lysette Anthony very poorly, since she spent most of the film just running through corridors and waiting to be rescued, and the producers has Lindsay Crouse dub all her dialogue because they thought an American accent would play better. Reportedly, Anthony really hates the film in retrospect. But she (and Crouse) did have some good moments in the early scenes. The film is also notable for featuring a pre-fame Liam Neeson in a supporting role as one of the outlaws Colwyn recruits to his cause, a traveling man with wives in multiple towns, although we only briefly meet one of them. There's remarkably little female presence in this film.
I thought I recognized the name of the film's writer Stanford Sherman, and it turns out he was a writer on Batman '66's second and third seasons, whose credits include the classic story where Penguin runs for mayor, and the debut episode of Batgirl. He also wrote the monumentally sexist "Nora Clavicle and the Ladies' Crime Club," which might explain why Krull gives women so little to do.
The film has a couple of Doctor Who actors in it. The cyclops Rell was played by the 6'7" Bernard Bresslaw, who played the first Ice Warrior to appear in the series. And the voice of the Beast was an uncredited Trevor Martin, who played the Doctor in a 1974 stage play.