Well Heavy Rain looks to be basically a bunch of Resident Evil style quicktime events strung together...
I will never watch the cutscenes in MGS4 again but I thought what gameplay there is, was very enjoyable. Short games don't really bother me because it makes it more fun going back to get a platinum. Games that are 25 hours + with multiple play throughs or require a ton of online play (I'm looking at you Killzone 2 and Socom) mean that I probably won't ever get one... If they ever patch MGS4 for trophies I will very much enjoy going back and playing it, hopefully with no kills or something to make it really fun.
Either way if the cut scenes are less than 10 minutes each then Uncharted 2 will be fine. The multiplayer beta alone convinced me to purchase the game. It will definitely be the best third person shooter on PS3 when it comes out.