The installer version of tetris blows, every knock-off of tetris does. Ide prefer to buy the legit thing made by the people who know it best. Besides I alway noticed after JB my ipod touch+iphone the keyboard slowed down, not something anyone wants to live with...
I had that for a while
i loved the tetris game
but jailbreak screwed my iPhone over twice
so i went back to normal and decided to wait for the app store
and the appstore version will work well with the rest of the phone
like not crashing when a text came in
as jailbreak tetris often did for me