The starting was quite good but as the story unfolded, it became illogical.
Calvin is an alien consisting of only muscles (no brain or neurons) and then just being a few cms big, it was able to crunch the hands of a full grown adult. Then was able to break past 2 firewalls and survive in deep space.
If that was not enough, in the end that alien was able to steer the escape pod to earth. If thats what a creature can learn in a few hours then thats insane