Having caught this film quite by accident, i felt gripped not only its innate cheesiness but also several little gems of direction and production design. If you can get past the stereotypes (doddery professor, beautiful daughter, brash American newsman), and the awful accents (isn't that policeman Irish, rather than Scottish?!) The Man From Planet X is a very watchable b-movie. The alien reminded me of the last days of the Spirit comic strip and the lonely croft amongst the billowing fog was a very stark image. Add to this the beautifully sleek (although wholly impractical) spaceship, typically 50s in design, some great chiarascuro cinematography (the alley abduction scene), plus that low-pitched camera outside the dungeon, and you've got a very technically engaging movie.
Never mind that the plot's got more holes than a string vest (where did all those soldiers come from?) and the acting and script are as wooden as a Scots pine dresser, enjoy it on a technical level if you can't engage with the human drama. As with many films of this ilk, the denoument was a bit hurried but all in all, this watches as well as (or dare i say, better than) any episode of Dr Who - with which it shares many similarities.