Yes, I watched Snow Devils and I had seen War of the Planets before. There was not much to redeem them. I didn't mind the special effects in either, because I appreciate the retro look...
But there's good retro and bad retro, and this was the latter. Plenty of shows and movies at the time had miniature ships flying on wires, but at least they made an effort to make them look like they were really moving under power. Here, the aircars and astronauts and even asteroids were blatantly swinging back and forth in an arc from a fixed point overhead -- they didn't even try to hide it. It wasn't just retro, it was lazy.
Not to mention the space station that was rotating swiftly in one long shot and then totally stationary in the immediately following closeup -- and whose internal gravity vector was perpendicular to what the rotation would've induced.
Sounds like prime MST3K fodder.
Portions of The Green Slime
were actually used in the unaired pilot/demo film for MST3K:
The pilot's on YouTube
-- it's actually pretty lame.