It did feel like it was a bit of a cop out that The Illusive Man was being controlled by the reapers, kind of brings his character down for me. Even so I still think he was great.

I actually wasn't aware of the fourth ending option. When I got to the final choice and noticed I still had my gun I randomly turned around and decided to shoot the reaper AI. When he said "The cycle continues" it was kind of an "oh crap" moment for me. It was a nice surprise but also kind of annoying because I had to go back through all that dialogue again to pick the ending I wanted.

I went with the synthesis ending. I know controlling the reapers is supposed to be the good ending, but now matter how paragon Shepard is, "absolute power corrupts absolutely" as they say. I figure having one person with power over the reapers is a bad idea. I'll admit I did get a bit choked up during the ending. No tears though.

I'll probably check out the other two endings later tonight or tomorrow.

Edit: I watched the other two endings. From a cinematic standpoint I thought the control ending was a bit weird. It's supposed to be a happy ending but the music and the way Shepard's voice sounded made it seem a bit sinister to me.

The destroy ending was pretty much as I expected it to be.

I also tried the renegade speech options for the confrontation with the Illusive Man and I thought they were more interesting than the paragon ones. And even though he's a great character putting a bullet in him was very satisfying.

I don't know the difference between the original and extended endings (I haven't seen the original) and I don't know whether people thought the extended cut fixed the issues that were there, but I thought the endings were great.