Underdeveloped
Please don't misunderstand when I say: Viewfinder is more than a tech demo, but not much more.
Its perspective-twisting mechanics are impressive, making for some pretty neat puzzles! And a few levels add compelling twists, like electric circuits (which must stay complete in snapshots) and abstract art-style switch-ups (which affect level geometry!). But the vast majority of its puzzles are shallow. Viewfinder never builds the complexity to compare to, say, Antichamber.
It has a storyline, framing and explaining its physically-impossible world, as well as audio recordings from a cast of background characters. But the narrative isn't convincingly connected to what you're doing in-game; it feels very bolted-on. And those characters aren't ... interesting. Viewfinder doesn't have the personality or the drama of a Portal, or even a Magrunner: Dark Pulse.
And outside of the puzzles, the game isn't all that well-polished. Voiceovers play over one another. Music is moody, but dull and repetitive. Menus look like they were slapped together last-minute.
You can pet a cat, though.

Viewfinder has some pretty awesome technology powering its core mechanics, and a basically functional game surrounding them. There are plenty of worse first-person puzzlers. There are plenty of better ones, too.
Better than: Qbeh-1: The Atlas Cube
Not as good as: Q.U.B.E.
Comparable to: Quantum Conundrum