IMDB totally trashes this film with a rating of 4.9. Ouch! However, I would argue that while Journey to the Seventh Planet has its flaws, it falls into the "so bad its good" category. There is something endearing about this film that I found quite enjoyable. Yes, the acting is a bit stiff and the dialogue over scientific. Yes, there are holes to be found in the plot and a number of details that defy explanation. But here's the good stuff:
The overall plot is actually quite decent. It takes the subject of "mind control by an alien being" into interesting territory where the ship's crew find their greatest fears and desires coming to life before their eyes.
Furthermore, I freakin' love the stop-motion cyclops rat monster [I don't know how else to describe it]. It's horrible but in a really entertaining way. It doesn't invoke terror as much as it does rolls of laughter. This scene alone is worth the price of admission!
John Agar [Attack of the Puppet People, Tarantula] make a nice 1950's space ship captain. He does it with the classic bravado of the period and hold the film together. he rest of the cast is fine as well.
Finally, the cinematography is actually quite decent for the limited budget. Yes, the exterior shots of the rocket flying through space are Ed Wood worthy [God-awful] but the shots on the surface of the planet work quite well.
So, be kind to Journey to the Seventh Planet. If you like cheesy 1950's Sci-Fi flix, then you will probably find this one enjoyable. It's not great filmmaking by any stretch of the imagination, but it's not a red hot mess either!
For more info check out the film's entry in IMDB.