Initial reactions to a major release are frequently more favourable than the settled view that emerges weeks later. Several parts of the process push in the same direction.
Early audiences are self-selected
The people who attend a first screening are those who arranged to be there, which usually means existing interest in the work or the people behind it.
Enthusiasm going in affects the experience, and someone who wanted to be in the room is more likely to find things to admire.
Later reviewers include people assigned to cover the release regardless of interest, and their verdicts are correspondingly cooler on average.
The conditions are unusually favourable
Premieres and festival screenings present work in excellent projection, in a full room, with an audience primed to respond.
Comedy plays better in a crowded room and spectacle plays better on a large screen, so the same work genuinely lands harder in those conditions.
Most viewers will never see it that way, which is one reason a reaction from a festival can seem inexplicable months later.
Immediate reactions are written in a specific state
Short reactions posted straight after a screening are composed while the strongest moments are still vivid and before weaknesses have surfaced.
Structural problems, thin characterisation and a weak ending tend to become apparent on reflection rather than on the way out of the room.
Considered reviews written days later routinely differ in emphasis from the same critic's first impression.
Access shapes the pool of early attendees
Invitations are issued by the distributor, and outlets that have covered similar work sympathetically are more likely to be included.
This is not usually explicit, but the effect is a first wave that skews toward people already disposed to the material.
As access widens, the range of opinion widens with it, which is the main reason aggregate scores drift downward in the first weeks.
Enthusiasm spreads faster than reservation
Strong praise is more shareable than qualified approval, so the earliest reactions that reach a wide audience are disproportionately the warmest ones.
A measured verdict published at the same time gets far less circulation, which distorts the apparent balance of early opinion.
Readers can correct for this by waiting for the full range of reviews, since the difference between the first reactions and the settled view is often substantial.