There are all sorts of subtleties when you've seen movies you call "bad." Sometimes you expected it to stink, while sometimes you're surprised it did. Some films are bad from the start, or throughout, or turn so near the end. Certain pictures fail multiple aspects of basic filmmaking, while others are competent but bland, and others still just have one fatal flaw.
Especially in the wake of Scream (god, I loved that movie), there was a strong run on studio-backed, teen-targeted slasher films. ABC, CBS, and NBC shows are usually about 20-some things or older, and the "new" networks, like Fox and The WB (later CW) got big numbers with primetime teen shows. That's why we got Nick Stahl and Katie Holmes in Disturbing Behavior, or Rebecca Gayheart and Tara Reid in Urban Legend. I Know What You Did Last Summer just happened to be the biggest disappointment.
Director Jim Gillespie's 1997 slasher/thriller actually had a lot of things going for it, hence my reaction. It was based on a 1970s novel, so it already had a publishable story outline to play with. The $17 Million budget was just fine, considering that the action-packed Aliens made do with $30-40 Mil 10 years earlier.
Was the cast stacked with the day's teen heartthrobs? Yes, but it was probably a best possible outcome situation. Hewitt can give respectable performances. I've seen three films with Prinz Jr., and he did just fine in those. Gellar can be quite solid, and Phillippe is considered a good actor by most everyone.
So IKWYDLS (because... no way would I make you read that again, even copy/paste is tiring) has lots of strengths. Many movie-goers will be drawn to the young pretty people, and "good people commit accidental crime, then cover it up and suffer" is a tried-and-true story type. What went wrong?
A large part is what they went into filming with, as well as the actual execution. The emotional drama didn't quite work. The relationship material didn't really work. The cast didn't have incredible chemistry, and the script could get quite flat.
Most damning, it wasn't scary. The bad guy in these movies is a person with a bright yellow fisherman's jacket, face hidden in a hood - and he kills people with a fishing hook. He torments teens with damning photos, a surprise beating or two, ransom-style notes, and by filling Hewitt's trunk with live seafood. This killer's profile, then, is bland and uninspired - unless maybe this was targeted to... New England audiences?... The Mediterranean?
Worse still, this movie gives viewers the anti-Scream treatment. In Craven's film, several victims effectively fight back against a murderer who sometimes stumbles and misses. This created tension in the scenes, invested us in the players, and added some dimension to the baddie.
In Gillespie's film, the bad guy's main activity for a long while is stalking and tormenting his victims through almost-blackmail... Then the "kill" switch flips - people run from him, the murderous mariner frequently arriving or disappearing like a ghost. This guy follows them as if he had a bloodhound's nose, even into locations he couldn't really scope out first.
He's... a ninja fisherman.
This is why I call I Know (nailed it) an "un-thriller." The attacks were seldom even kind of frightening, the enemy is virtually omniscient and unstoppable, you're not invested in anyone (save Phillippe's role, whom you want to die), and the chase scenes are unsatisfying. Scary movies have to be scary or else they fail their basic job.
It's right there in the title. Those words, framed in a thriller/suspense context, are compelling. And yet that is one seriously ungainly film title, to the point of being so hard to say or write that it becomes stupid. This one fact neatly reflects on the sensibilities of the whole production.