First off, consider that this film is nearly fifty years old! Yet, it still stands up as one of the great films of all time. I wonder how many of todays throwaway celluloid productions will still be talked about in 2050?
The story is simple, yet solid enough and the effects are nothing short of phenomenal for the day. I can still recall the first time I watched this, as a kid, when the monster enters the force-field protecting the ship and you got to see its outline for the first (and only) time. Had me shivering in fear, I can tell you. Looks dated today, but still more than effective enough.
The scenes with the tiger show their age now. You can see the outline where the tiger was matted into the shots with Altaira, but they are only just visible.
Likewise, the effect whereby the creature melts its way through the Krell doors are wonderfully done.
It's also amazing to see Leslie Nielsen (better remembered for the Airplane and Naked Gun movies) as a young, but still mature man. He was 30 when this film came out! Nearly 80 now!
All in all a good movie that is sure to continue being a favourite for years to come. Timeless.