The issue isn't that it's short--the first Portal is a masterpiece--it's that even though it's short, the late game content strongly feels like the developers ran out of ideas and the game just kind of shambles across the finish line. I mean, the first half of the game really explores what you can do with their interesting mechanics in a very fun way, but the second half... There is one dungeon in there () that is still pretty good, but it's more of one last bright spot on the game's stumble across the finish line.

Not to say the game isn't worth playing--it's worth the price of admission for the beautiful art and music alone--but putting aside the game's really strong first impressions, the game as a whole is probably just "pretty okay."