Overall It Came From Below is a very disappointing movie. Even for a low budget film... it's pretty bad. The acting is unimpressive... the plot is nonsensical... the characters are idiotic... and the creature and its abilities are unexplained and erratic.
You have characters making truly idiotic choices, which even for a horror movie make absolutely no sense. You have a creature that has mind control abilities... sometimes... when it's convenient... and not others... which feeds on people... sometimes... and other times ignores them completely... None of it makes any real sense.
Most of the movie takes place in a dark cave, with little light, and little idea what's actually happening. The insane amount of shaky cam doesn't help at all.
The creature looks decent. Honestly it could have been a decent movie if not so horrifically written, as it had an okay concept. But it's just a horrible mess that's not worth watching.