The endings are too farfetched IMO, they were beyond any bit of the story line to give reasons or answers. There were simply too many "what the...? huh?" moments that threw everything around like a hot potato. I'm honestly a paragon through and through, I considered The Illusive Man an intelligent but very clouded individual, and I was dead set on making sure his plans were stopped, simply because his methods were absolutely immoral.
On my first play through i had to shoot him in the end, and i said to myself "ahhh.... finally, his sick and twisted scheme has finally come to an end!" and then i hear Shepard say "So the illusive man was right all along!" and the Illusive Man choice was blue, to symbolize paragon!
My response? You guessed it! "What the...? huh?" The entire thing was completely backwards. Now i didn't care what was what, I was going to finish what i played this ENTIRE GAME to do, 'renegade' or not. That ending showed not only my romance choice could somehow teleport and ended up on the normandy, but the normady was in a mass effect jump too, somehow ending up on a remote planet that just so happened to support life. Then i found Shepard stuck under rubble, alive... besides the theories going around, i had no idea what was going on, but i also realized that my team practically ditched me...
TL:DR - This game felt like running at 1000MPH then tripping off of the edge of a cliff at the finish line. Fun till the end.