Not entirely devoid of amusement but this is a good five years too late to an already thin party. Does spoofing the not-very-good have even less merit than poking fun at something better? This comes off a poor second to the agreeable pastiche of Young Frankenstein and Blazing Saddles (even High Anxiety) and when the joker isn't as good as the victim, you have a problem.
I can really appreciate Mel Brook's style but its a thin line between being quirky and kinda cute and being utterly mindless and predictable. Spaceballs feels like a man walking on top of that line: Sometimes he balances to the right others to the left, but always having a fun pacing throughout making the man's walk not as uneventful as it might have been.
True story: I was working at a furniture warehouse a few years ago and my co-worker told me to go look for this package buried deep into this truck trailer. After about 20 minutes of looking he walks up to the end of the trailer and yells, "Have you found it yet?" and I say, "We ain't found shit!". He immediately busts a gut. I love this movie. It's all about Mel Brooks.