I played fahrenheit (or indigo prophecy) and at first thought it was great, because even though the action scenes were all QTEs, the story seemed to be branching and freeform. It didn't live to that at all, conversations yielded slightly different results, but any key information was always given, the rest is optional fluff. The game just wanted to send you down one path and pretend you chose it. There were some key decisions, but frankly it was done better in many other role playing games. The second half was completely bananas too.
As for the QTEs in that game, it became simply tiresome after a while, when it was always the same thing (press a direction on one of the analogues, or hammer R1), that it just became a distraction to the cutscene you were trying to watch. It wasn't engaging, and the inputs felt like they had no relation to what was happening on screen, you just pressed buttons to keep watching. It would honestly have been better with none at all.
From what I've seen Heavy rain seems to be taking nearly all it's old conventions from that game, aside from the promised more open storyline. From gameplay videos, it seems again, this doesn't even seem to affect most situations, but I'll reserve judgement on that.
I accept that in this type of game the gameplay is constricted by the narrative, but the gameplay doesn't have to be naff. Right now it looks like absolute shite. I think a system like mirror's edge, of all things, would be better i.e. one button performs a general type of action in a cutscene and each action could make the cutscene play differently, with less prompts. They can retain pacing, and you have to more actively engage with the scene, rather than an arbitrary button prompt every 6 seconds which breaks immersion more than anything.
If it's anything like fahrenheit though, It'll choke on it's own ambition when it isn't completely realised. Small miracle if it pulls it off.