Another World has been remembered for over two decades now because of the uniquely cohesive experience and sleek vectorized visuals it offers, from a time where graphics and storytelling were often terse and stilted.
While this game is short, not much longer than two hours, those two hours have been solely designed by French artist Eric Chahi, and intimate attention has been paid to the detailed backgrounds, foregrounds and animations. Pacing and level design have been carefully decided to fit the overall theme.
This comes from an era where all this fit on two floppy disks -- this entire game had to fit in just under 3MB. So while music and sound may seem sparse, and some areas seem underpopulated or underdetailed, just realize this entire game was the same size as a modern-day high-resolution background image.
As a result of being designed around these limitations, what the game does have and does do, it does very well. Another World is a game that manages to have both atmosphere and style, in a tightly-knit package.
As for the actual gameplay, it is enjoyable -- combat is intense and quick, leading to frequent deaths but the kind of feeling that will keep you on your toes. Puzzles are sometimes unusual, I think more an indication of the era the game came from -- puzzle logic even in most story-driven games for the time (point-and-click adventure games) were often unforgiving and exacting. So while this game has some odd puzzles, its quick respawns and common checkpoints often allow you to figure out the way through quickly without too much frustration from quick successive deaths.
Overall, a surprisingly unique and strong narrative for the time, relying on virtually no written or spoken word. As for it's price point: 10 dollars is not unfair to ask, and those who have played this before might be willing to drop that much for the nostalgia factor. For most other people, 10 dollars can certainly get you a lot more than two hours of gameplay. But, as a milestone in video game history, and as an experience that still stands on its own merits, it's still worth giving it your time -- it doesn't ask for much.
P.S. Another World will likely be going on seasonal sale at 2.50USD from its current 10USD price point, as it has during the Summer 2014 Steam Sale. If you're on the fence, I'd strongly recommend picking it up during the next wave of seasonal sales.