This has everything I like about Tilda Swinton's best movies, plus some of what I dislike about her lesser works. Dislikes include low-budget effects and cryptic finales, but maybe that's part of the charm of these movies.
The good, of course, comes from Swinton. She plays a geek girl (Rosetta Stone), but plays the role with respect. She's shy, especially shy around men, and fiercely intelligent. Swinton also plays Stone's three clones: Ruby, Olive, and Marinne. It's a bit ham-handed, but the four roles are distinguished by very different wigs, and the clones by color coding: red, green, and ultramarine. Swinton's real achievement is in her physical presence[s] - the body language of each character is distinctly the character's own. Rosetta is especially good in her my-gawd-i'm-a-mother moments, painfully but realistically unsure, and over cautious as a result.
The plot device is a bit odd: almost vampiric in an AIDS-era kind of way, but with a computer-y angle and a gentle resolution in the end. Rosetta and Ruby each find romantic resolutions of their own. Olive and Marinne seem to find each other - and something more. "As easy as baking brownies." The end is enigmatic, but good enough, and leaves a few questions open.
It's a good indy movie. That means it's not for everyone, but I came away happy.