On IMDb 'Colossal' is described as "quirky". Be warned: any film that is described as 'quirky' is usually devoid of plot and merely a vehicle for intellectual masturbation. This film is very 'quirky'. First off, it never really starts: we waited for about an hour (and a short snooze for me) for something tangible to happen. It didn't. Note to the producers: something has to happen. If it doesn't, people will walk out (we did).
Second note to the producers: someone needs to tell Anne Hathaway she can't act. OK, I'll do it: "Anne, you can't act".
Anne Hathaway was four months pregnant when this was filmed - and she looks pregnant. Third note to the producers: Don't cast someone who is obviously pregnant as somebody who is not pregnant (people will wonder why she waddles).
A movie's first hurdle is to entertain - if it fails to entertain it fails. This fails.
The characters were uniformly unpleasant: there's no-one you care about.
The script was loose: a number of scenes have you groping to find the answer to "what did that scene add?".
This is a bad film: don't waste your time, don't waste your money and avoid this like a terminal illness (yes, it is THAT bad).