Tris Developer Noah Witherspoon has conceded to removing his app from the App Store after pressure from the owner of the copyright for Tetris. Tetris offers its own app for $9.99, while Tris is free.
Macworld reviewed both games, and found the official version, developed by EA, lacking. It takes about 30 seconds to load, and you can't listen to your own music while playing. Tris [app store link] isn't perfect either, rotating pieces the wrong way, and doesn't offer "ghosting": seeing where pieces will land before they drop (which always seemed like cheating to me).
The Tetris Company is well known for aggressively enforcing its copyright on the game. Tetris clone Quinn, for example, goes to great lengths to distance itself from Tetris: it doesn't even mention the word except for a small disclaimer at the bottom of the screen.
Witherspoon understands that The Tetris Company is entitled to enforce its copyrights, but said on his blog "the approach they're taking seems to me little more than bullying." Witherspoon is a student, and admits he lacks the means to pursue the case through the courts.
Witherspoon will pull Tris from the App Store on Wednesday. He wants to offer the app at some point in the future, but is evaluating his options.