I honestly wish this was not the case, but in ME1 and ME2 I instantly restarted, full of ideas as to how my Renegade male soldier would do things differently to my Paragon female vanguard.
ME3? I tried to play again, and quit as soon as I got to a player controlled section. I tried ME1 for a 'full' run through, quit.
What is the point? I can nuke the Rachni, have Ashley kill Wrex, sell Legion and turn the Collector base into apartments and I would still have the same 3, near identical, endings. Should it be final, Bioware have done catastrophic damage to their games with the ending to ME3. But I have faith that the company simply could not end their Magnum Opus like this, they are too brilliant as game designers and the rest of the game was too damned good for them to release it without somebody saying "hang on guys..."
I have faith that they have something up their sleeve, and are soon to reveal their Quad as the biggest in the Galaxy. And when that day comes, they will be declared gods and this will go down in history as the greatest ploy in the medium's history. But right now, I just can't pretend that I care about playing through again.
Edit: I am not saying that it has ruined the experiences have already had. I will fondly remember everything up to this point. Mass Effect has been my absolute favourite video game experience, and I won't let the endings ruin that. I just won't play it again until they fix them.