My experience in a diceless game is missed. Overall, I wouldn't do it again, but I played in one for a year and a half about 8 years ago.  The dm claimed to be prerolling dice but it was obvious that he was just pushing the story along by however  he thought it should go.  After playing in a couple of good dice games after that, I can't say i could ever go back.  It was an ok experience and the role playing was the best, but there was a genuine feeling of lack of control. 
It felt more like I was guiding an a a glider to a safe landing as opposed to flying a plain.  
In the same token some of the dice rolls in my game are solely up to me the dm and not the players. All listen, spot, initiative and trapfinding search rolls.