I didn't find 'The Butterfly Effect' "achingly dull", as one of the unkinder IMDB reviewers thought, but it dropped off my credibility scale well under halfway through and only stopped me escaping to the loo before the end because some of the characters sustained my interest even when I was otherwise bored or mildly appalled.
Without going into gore, some of the clichés the movie fails to avoid are very unpleasant, but they are clichés of the kind that makes life itself a horrible place sometimes.
It's a film I'll remember, for certain episodes, and has some amusing moments as well, but the "serious social issues" the Kid and I will be talking about in its wake were in the right places at the wrong time in the wrong way.
She enjoyed it, but hasn't rated it yet. For a whole that turned out to be so much less than some of its parts, I can't manage more than a 3.5/10, even for effort. 'The Butterfly Effect' does try very hard to succeed, and maybe that's half the problem. It makes me want to be more generous to it.

That prolific 'unemployed critic (IMDb)' who didn't like it at all — though many did, including Michelle Mauriere right here at BC — suggests that "the similarly themed 2001 film 'Donnie Darko' is a much better take on the time bending mysteries of the brain". If the rotten tomatoes are anything to go by, that looks like a sound point.